Python 2.5 Quick Reference |
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Contents
Front matterVersion 2.5 (What's new?)Check updates at http://rgruet.free.fr/#QuickRef. Please report errors, inaccuracies and suggestions to Richard Gruet (pqr at rgruet.net).
Useful links :
Tip: From within the Python interpreter, type Invocation Optionspython[w] [-dEhimOQStuUvVWxX?] [-c command | scriptFile | - ] [args]
Environment variables
Notable lexical entitiesKeywordsand del for is raise
Identifiers(letter | "_") (letter | digit | "_")*
String literals2 flavors:str (standard 8 bits locale-dependent strings, like ascii, iso 8859-1, utf-8, ...) and unicode (16 or 32 bits/char in utf-16 mode or 32 bits/char in utf-32 mode).
Boolean constants (since 2.2.1)
Numbers
Sequences
Dictionaries (Mappings)
Dictionaries (type
Keys must be of a hashable type; Values can be any type.
Operators and their evaluation order
Basic types and their operationsComparisons (defined between any types)
None
Boolean operators
Numeric typesFloats, integers, long integers, Decimals.
Operators on all numeric types
Bit operators on integers and long integers
Complex Numbers
Numeric exceptions
Operations on all sequence types (lists, tuples, strings)
Operations on mutable sequences (type
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| Operation | Result | Notes |
|---|---|---|
| len(d) | The number of items in d | |
| dict() dict(**kwargs) dict(iterable) dict(d) |
Creates an empty dictionary. Creates a dictionary init with the keyword args kwargs. Creates a dictionary init with (key, value) pairs provided by iterable. Creates a dictionary which is a copy of dictionary d. |
|
| d.fromkeys(iterable, value=None) | Class method to create a dictionary with keys provided by iterator, and all values set to value. | |
| d[k] | The item of d with key k | (1) |
| d[k] = x | Set d[k] to x | |
| del d[k] | Removes d[k] from d | (1) |
| d.clear() | Removes all items from d | |
| d.copy() | A shallow copy of d | |
| d.has_key(k) k in d |
True if d has key k, else False |
|
| d.items() | A copy of d's list of (key, item) pairs | (2) |
| d.keys() | A copy of d's list of keys | (2) |
| d1.update(d2) | for k, v in d2.items(): d1[k] = vSince 2.4, update(**kwargs) and update(iterable) may also be used. |
|
| d.values() | A copy of d's list of values | (2) |
| d.get(k, defaultval) | The item of d with key k | (3) |
| d.setdefault(k[,defaultval]) | d[k] if k in d, else defaultval(also setting it) | (4) |
| d.iteritems() | Returns an iterator over (key, value) pairs. | |
| d.iterkeys() | Returns an iterator over the mapping's keys. | |
| d.itervalues() | Returns an iterator over the mapping's values. | |
| d.pop(k[, default]) | Removes key k and returns the corresponding value.
If key is not found, default is returned if given, otherwise KeyError is raised. |
|
| d.popitem() | Removes and returns an arbitrary (key, value) pair from d |
TypeError is raised if key is not acceptable.KeyError is raised if key k is not in the map. None is returned. None is returned and added to map. str & unicode)str and unicode types share a common base class
basestring.| Operation | Result | Notes |
|---|---|---|
| s.capitalize() | Returns a copy of s with only its first character capitalized. | |
| s.center(width) | Returns a copy of s centered in a string of length width. | (1) |
| s.count(sub[ ,start[,end]]) | Returns the number of occurrences of substring sub in string s. | (2) |
| s.decode([ encoding[,errors]]) | Returns a unicode string representing the decoded version of str s,
using the given codec (encoding). Useful when reading from a file or a I/O function that handles
only str. Inverse of encode. |
(3) |
| s.encode([ encoding[,errors]]) | Returns a str representing an encoded version of s. Mostly used to encode a
unicode string to a str in order to print it or write it to a file
(since these I/O functions only accept str), e.g. u'légère'.encode('utf8').
Also used to encode a str to a str, e.g. to zip (codec 'zip')
or uuencode (codec 'uu') it. Inverse of decode. |
(3) |
| s.endswith(suffix [,start[,end]]) | Returns True if s ends with the specified suffix, otherwise return false.
Since 2.5 suffix can also be a tuple of strings to try. |
(2) |
| s.expandtabs([ tabsize]) | Returns a copy of s where all tab characters are expanded using spaces. | (4) |
| s.find(sub[ ,start[,end]]) | Returns the lowest index in s where substring sub is found. Returns -1 if sub is not found. | (2) |
| s.index(sub[ ,start[,end]]) | like find(), but raises ValueError when the substring is not found. |
(2) |
| s.isalnum() | Returns True if all characters in s are alphanumeric, False otherwise. |
(5) |
| s.isalpha() | Returns True if all characters in s are alphabetic, False otherwise. |
(5) |
| s.isdigit() | Returns True if all characters in s are digit characters, False otherwise. |
(5) |
| s.islower() | Returns True if all characters in s are lowercase, False otherwise. |
(6) |
| s.isspace() | Returns True if all characters in s are whitespace characters, False otherwise. |
(5) |
| s.istitle() | Returns True if string s is a titlecased string, False otherwise. |
(7) |
| s.isupper() | Returns True if all characters in s are uppercase, False otherwise. |
(6) |
| separator.join(seq) | Returns a concatenation of the strings in the sequence seq, separated by string
separator, e.g.: ",".join(['A', 'B', 'C']) -> "A,B,C" |
|
| s.ljust/rjust/center(width[, fillChar=' ']) | Returns s left/right justified/centered in a string of length width. | (1), (8) |
| s.lower() | Returns a copy of s converted to lowercase. | |
| s.lstrip([chars] ) | Returns a copy of s with leading chars (default: blank chars) removed. | |
| s.partition(separ) | Searches for the separator separ in s, and returns a tuple (head, sep, tail)
containing the part before it, the separator itself, and the part after it. If the separator is not
found, returns s and two empty strings. |
|
| s.replace(old, new[, maxCount =-1]) | Returns a copy of s with the first maxCount (-1: unlimited) occurrences of substring old replaced by new. | (9) |
| s.rfind(sub[ , start[, end]]) | Returns the highest index in s where substring sub is found. Returns -1 if sub is not found. | (2) |
| s.rindex(sub[ , start[, end]]) | like rfind(), but raises ValueError when the substring is not found. |
(2) |
| s.rpartition(separ) | Searches for the separator separ in s, starting at the end of s, and returns a
tuple (tail, sep, head) containing the part before it, the separator itself, and the part
after it. If the separator is not found, returns two empty strings and s. |
|
| s.rstrip([chars]) | Returns a copy of s with trailing chars(default: blank chars) removed, e.g.
aPath.rstrip('/') will remove the trailing '/'from aPath if it exists |
|
| s.split([ separator[, maxsplit]]) | Returns a list of the words in s, using separator as the delimiter string. | (10) |
| s.rsplit([ separator[, maxsplit]]) | Same as split, but splits from the end of the string. |
(10) |
| s.splitlines([ keepends]) | Returns a list of the lines in s, breaking at line boundaries. | (11) |
| s.startswith(prefix [, start[, end]]) | Returns True if s starts with the specified prefix, otherwise returns False.
Negative numbers may be used for start and end.
Since 2.5 prefix can also be a tuple of strings to try. |
(2) |
| s.strip([chars]) | Returns a copy of s with leading and trailing chars(default: blank chars) removed. | |
| s.swapcase() | Returns a copy of s with uppercase characters converted to lowercase and vice versa. | |
| s.title() | Returns a titlecased copy of s, i.e. words start with uppercase characters, all remaining cased characters are lowercase. | |
| s.translate(table [, deletechars]) | Returns a copy of s mapped through translation table table. | (12) |
| s.upper() | Returns a copy of s converted to uppercase. | |
| s.zfill(width) | Returns the numeric string left filled with zeros in a string of length width. |
sys.getdefaultencoding(), can be changed via
sys.setdefaultencoding(). Optional argument errors may be given to set
a different error handling scheme. The default for errors is 'strict', meaning
that encoding errors raise a ValueError. Other possible values are 'ignore' and
'replace'. See also module codecs.False if string s does not contain at least one character. False if string s does not contain at least one cased character. None, any whitespace string is a separator.
If maxsplit is given, at most maxsplit splits are done. formatString % args --> evaluates to a string
%[flag][width][.precision] formatCodewhere formatCode is one of c, s, i, d, u, o, x, X, e, E, f, g, G, r, % (see table below).
| Format string | Result |
|---|---|
'%3d' % 2 | ' 2' |
'%*d' % (3, 2) | ' 2' |
'%-3d' % 2 | '2 ' |
'%03d' % 2 | '002' |
'% d' % 2 | ' 2' |
'%+d' % 2 | '+2' |
'%+3d' % -2 | ' -2' |
'%- 5d' % 2 | ' 2 ' |
'%.4f' % 2 | '2.0000' |
'%.*f' % (4, 2) | '2.0000' |
'%0*.*f' % (10, 4, 2) | '00002.0000' |
'%10.4f' % 2 | ' 2.0000' |
'%010.4f' % 2 | '00002.0000' |
'%s has %03d quote types.' % ('Python', 2) == 'Python has 002 quote types.'a = '%(lang)s has %(c)03d quote types.' % {'c':2, 'lang':'Python'}
(vars() function very handy to use on right-hand-side) | Code | Meaning |
|---|---|
| d | Signed integer decimal. |
| i | Signed integer decimal. |
| o | Unsigned octal. |
| u | Unsigned decimal. |
| x | Unsigned hexadecimal (lowercase). |
| X | Unsigned hexadecimal (uppercase). |
| e | Floating point exponential format (lowercase). |
| E | Floating point exponential format (uppercase). |
| f | Floating point decimal format. |
| F | Floating point decimal format. |
| g | Same as "e" if exponent is greater than -4 or less than precision, "f" otherwise. |
| G | Same as "E" if exponent is greater than -4 or less than precision, "F" otherwise. |
| c | Single character (accepts integer or single character string). |
| r | String (converts any python object using repr()). |
| s | String (converts any python object using str()). |
| % | No argument is converted, results in a "%" character in the result. (The complete specification is %%.) |
| Flag | Meaning |
|---|---|
| # | The value conversion will use the "alternate form". |
| 0 | The conversion will be zero padded. |
| - | The converted value is left adjusted (overrides "-"). |
| (a space) A blank should be left before a positive number (or empty string) produced by a signed conversion. | |
| + | A sign character ("+" or "-") will precede the conversion (overrides a "space" flag). |
substitute or safe_substitute methods (substitute throws KeyError if a
key is missing while safe_substitute ignores it) :
t = string.Template('Hello $name, you won $$$amount') # (note $$ to literalize $)
t.substitute({'name': 'Eric', 'amount': 100000}) # -> u'Hello Eric, you won $100000'
file). Created with built-in functions
open() [preferred] or its alias
file(). May be created
by other modules' functions as well.| Operation | Result |
|---|---|
| f.close() | Close file f. |
| f.fileno() | Get fileno (fd) for file f. |
| f.flush() | Flush file f's internal buffer. |
| f.isatty() | 1 if file f is connected to a tty-like dev, else 0. |
| f.next() | Returns the next input line of file f, or raises StopIteration when EOF is hit.
Files are their own iterators. next is implicitely called by
constructs like for line in f: print line. |
| f.read([size]) | Read at most size bytes from file f and return as a string object. If size omitted, read to EOF. |
| f.readline() | Read one entire line from file f. The returned line has a trailing \n, except possibly at EOF. Return '' on EOF. |
| f.readlines() | Read until EOF with readline() and return a list of lines read. |
| f.xreadlines() | Return a sequence-like object for reading a file line-by-line without reading the entire file into memory. From 2.2, use rather: for line in f (see below). |
| for line in f: do something... | Iterate over the lines of a file (using readline) |
| f.seek(offset[, whence=0]) | Set file f's position, like "stdio's fseek()". whence == 0 then use absolute indexing. whence == 1 then offset relative to current pos. whence == 2 then offset relative to file end. |
| f.tell() | Return file f's current position (byte offset). |
| f.truncate([size]) | Truncate f's size. If size is present, f is truncated to (at most) that size, otherwise f is truncated at current position (which remains unchanged). |
| f.write(str) | Write string to file f. |
| f.writelines(list) | Write list of strings to file f. No EOL are added. |
EOFError IOError set and frozenset (immutable set). Sets are unordered collections of unique
(non duplicate) elements. Elements must be hashable. frozensets are hashable (thus can be
elements of other sets) while sets are not. All sets are iterable.Set and ImmutableSet were
available in the module sets.This module remains in the 2.4 std library
in addition to the built-in types.| Operation | Result |
|---|---|
| set/frozenset([iterable=None]) | [using built-in types] Builds a set or frozenset
from the given iterable (default: empty), e.g. set([1,2,3]), set("hello").
|
| Set/ImmutableSet([iterable=None]) | [using the sets module] Builds a Set or ImmutableSet
from the given iterable (default: empty), e.g. Set([1,2,3]).
|
| len(s) | Cardinality of set s. |
| elt in s / not in s | True if element elt belongs / does not belong to
set s. |
| for elt in s: process elt... | Iterates on elements of set s. |
| s1.issubset(s2) | True if every element in s1 is in s2. |
| s1.issuperset(s2) | True if every element in s2 is in s1. |
| s.add(elt) | Adds element elt to set s (if it doesn't already exist). |
| s.remove(elt) | Removes element elt from set s.
KeyError if element not found. |
| s.clear() | Removes all elements from this set (not on immutable sets!). |
| s1.intersection(s2) or s1&s2 | Returns a new Set with elements common to s1 and s2. |
| s1.union(s2) or s1|s2 | Returns a new Set with elements from both s1 and s2. |
| s1.difference(s2) or s1-s2 | Returns a new Set with elements in s1 but not in s2. |
| s1.symmetric_difference(s2) or s1^s2 | Returns a new Set with elements in either s1 or s2 but not both. |
| s.copy() | Returns a shallow copy of set s. |
| s.update(iterable) | Adds all values from iterable to set s. |
mxDateTime.
- Module objects
- Class objects
- Class instance objects
- Type objects (see module: types)
- File objects (see above)
- Slice objects
- Ellipsis object, used by extended slice notation (unique, named
Ellipsis)- Null object (unique, named
None)- XRange objects
- Callable types:
- User-defined (written in Python):
- User-defined Function objects
- User-defined Method objects
- Built-in (written in C):
- Built-in Function objects
- Built-in Method object
- Internal Types:
- Code objects (byte-compile executable Python code: bytecode)
- Frame objects (execution frames)
- Traceback objects (stack trace of an exception)
| Statement | Result |
|---|---|
| pass | Null statement |
| del name[, name]* | Unbind name(s) from object. Object will be indirectly (and automatically) deleted only if no longer referenced. |
| print[>> fileobject,] [s1 [, s2 ]* [,] | Writes to sys.stdout, or to fileobject if supplied. Puts spaces between arguments.
Puts newline at end unless statement ends with comma. Print is not required when running interactively,
simply typing an expression will print its value, unless the value is None. |
| exec x [in globals [, locals]] | Executes x in namespaces provided. Defaults to current namespaces. x can be a string, open file-like object
or a function object. locals can be any mapping type, not only a regular Python dict.
See also built-in function execfile. |
| callable(value,... [id=value] , [*args], [**kw]) | Call function callable with parameters. Parameters can be passed by name or be omitted if function defines
default values. E.g. if callable is defined as "def callable(p1=1, p2=2)""callable()" <=> "callable(1, 2)"*args is a tuple of positional arguments. **kw is a dictionary of keyword arguments. |
| Operator | Result |
Notes
|
|---|---|---|
| a = b | Basic assignment - assign object b to label a |
(1)(2)
|
| a += b | Roughly equivalent to a = a + b |
(3)
|
| a -= b | Roughly equivalent to a = a - b |
(3)
|
| a *= b | Roughly equivalent to a = a * b |
(3)
|
| a /= b | Roughly equivalent to a = a / b |
(3)
|
| a //= b | Roughly equivalent to a = a // b |
(3)
|
| a %= b | Roughly equivalent to a = a % b |
(3)
|
| a **= b | Roughly equivalent to a = a ** b |
(3)
|
| a &= b | Roughly equivalent to a = a & b |
(3)
|
| a |= b | Roughly equivalent to a = a | b |
(3)
|
| a ^= b | Roughly equivalent to a = a ^ b |
(3)
|
| a >>= b | Roughly equivalent to a = a >> b |
(3)
|
| a <<= b | Roughly equivalent to a = a << b |
(3)
|
first, second = l[0:2] # equivalent to: first=l[0]; second=l[1]
[f, s] = range(2) # equivalent to: f=0; s=1
c1,c2,c3 = 'abc' # equivalent to: c1='a'; c2='b'; c3='c'
(a, b), c, (d, e, f) = ['ab', 'c', 'def'] # equivalent to:
a='a'; b='b'; c='c'; d='d'; e='e'; f='f'
x,y = y,x swaps x and y.
a = b = c = 0
list1 = list2 = [1, 2, 3] # list1 and list2 points to the same list (l1 is l2)
result = (whenTrue if condition else whenFalse)
if condition:
result = whenTrue
else:
result = whenFalse
| Statement | Result |
|---|---|
| if condition: suite [elif condition: suite]* [else: suite] |
Usual if/else if/else statement. See also Conditional Expressions. |
| while condition: suite [else: suite] |
Usual while statement. The else suite is executed after loop exits,
unless the loop is exited with break. |
| for element in sequence: suite [else: suite] |
Iterates over sequence, assigning each element to element. Use built-in
range function to iterate a number of times. The else suite
is executed at end unless loop exited with break. |
| break | Immediately exits for or while loop. |
| continue | Immediately does next iteration of for or while loop. |
| return [result] | Exits from function (or method) and returns result (use a tuple to return
more than one value). If no result given, then returns None. |
| yield expression | (Only used within the body of a generator function, outside a try of a
try..finally). "Returns" the evaluated expression. |
| Statement | Result |
|---|---|
| assert expr[, message] | expr is evaluated. if false, raises exception AssertionError with message.
Before 2.3, inhibited if __debug__ is 0. |
| try: block1 [except [exception [, value]: handler]+ [else: else-block] |
Statements in block1 are executed. If an exception occurs, look in except
clause(s) for matching exception(s). If matches or bare except, execute
handler of that clause. If no exception happens, else-block in else
clause is executed after block1. If exception has a value, it is put in variable
value. exception can also be a tuple of exceptions, e.g.
except(KeyError, NameError), e: print e. |
| try: block1 finally: final-block |
Statements in block1 are executed. If no exception, execute final-block (even if
block1 is exited with a return, break or continue
statement). If exception did occur, execute final-block and then immediately re-raise exception.
Typically used to ensure that a resource (file, lock...) allocated before the try is freed
(in the final-block) whatever the outcome of block1 execution.
See also the with statement below. |
| try: block1 [except [exception [, value]: handler1]+ [else: else-block] finally: final-block |
Unified try/except/finally. Equivalent to a try...except nested
inside a try..finally [PEP341].
See also the with statement below. |
|
with allocate-expression [as variable] with-block |
Alternative to the try...finally structure
[PEP343].allocate-expression should evaluate to an object that supports the context management protocol, representing a resource. This object may return a value that can optionally be bound to variable (variable is not assigned the result of expression). The object can then run set-up code before with-block is executed and some
clean-up code is executed after the block is done, even if the block raised an exception.Standard Python objects such as files and locks support the context management protocol: with open('/etc/passwd', 'r') as f: # file automatically closed on block exitYou can also write your own context managers. In 2.5 the statement must be enabled by: from __future__ import with_statement.
The statement will always be enabled in Python 2.6.
|
| raise exceptionInstance | Raises an instance of a class derived from Exception (preferred form of raise). |
| raise exceptionClass [, value [, traceback]] | Raises exception of given class exceptionClass with optional value value. Arg traceback specifies a traceback object to use when printing the exception's backtrace. |
| raise | A raise statement without arguments re-raises the last exception raised in the current function. |
class TextException(Exception): pass
try:
if bad:
raise TextException()
except Exception:
print 'Oops' # This will be printed because TextException is a subclass of Exception
str().StandardError, itself derived from Exception.BaseException. Raising strings as exceptions is now deprecated
(warning).sys.path).
Since 2.3, they may reside in a zip file [e.g. sys.path.insert(0, "aZipFile.zip")].
from __future__ import absolute_import: will probably be adopted in 2.7.import X will look up for module X in sys.path first (absolute import).import .X (with a dot) will still search for X in the current package first,
then in builtins (relative import).import ..X will search for X in the package containing the current one, etc...__init__.py (possibly empty). [package.[package...].module.symbol.| Statement | Result |
|---|---|
| import module1 [as name1] [, module2]* | Imports modules. Members of module must be referred to by qualifying with [package.]module name, e.g.:
import sys; print sys.argvmodule1 renamed as name1, if supplied. |
| from module import name1 [as othername1][, name2]* | Imports names from module module in current namespace.
from sys import argv; print argvname1 renamed as othername1, if supplied. [2.4] You can now put parentheses around the list of names in a
from module import names statement (PEP 328). |
| from module import * | Imports all names in module, except those starting with "_".
Use sparsely, beware of name clashes!
from sys import *; print argvOnly legal at the top level of a module. If module defines an __all__ attribute, only names listed in __all__
will be imported.NB: " from package import *" only imports the symbols defined in the
package's __init__.py file, not those in the package's modules ! |
| global name1 [, name2] | Names are from global scope (usually meaning from module) rather than local (usually meaning only in function). E.g. in function without global statements, assuming "x" is name that hasn't been
used in function or module so far:- Try to read from "x" -> NameError- Try to write to "x" -> creates "x" local to function If "x" not defined in fct, but is in module, then: - Try to read from "x", gets value from module - Try to write to "x", creates "x" local to fct But note "x[0]=3" starts with search for "x", will use to global "x" if no local "x". |
def funcName ([paramList]):Creates a function object and binds it to name funcName.
suiteparamList ::= [param [, param]*]
param ::= value | id=value | *id | **id
return to return (None) from the function, or return value to
return value. Use a tuple to return more than one value, e.g. return 1,2,3arg=value specify a default value
(evaluated at function def. time). They can only appear last in the param list, e.g. foo(x, y=1, s='')def foo(x, *args): ... is called foo(1, 2, 3), then args will contain
(2,3).def foo(x, **kwargs): ... is called foo(1, y=2, z=3), then kwargs will contain
{'y':2, 'z':3}. if def foo(x, *args, **kwargs): ... is called foo(1, 2, 3, y=4, z=5),
then args will contain (2, 3), and kwargs will contain {'y':4, 'z':5}def f1(x, *args, **kwargs):
f2(*args, **kwargs)
class className [(super_class1[, super_class2]*)]:Creates a class object and assigns it name className.
suite
suite may contain local "defs" of class methods and assignments to class attributes.
class MyClass (class1, class2): ...
Creates a class object inheriting from both class1 and class2. Assigns new class object to name MyClass.
class MyClass: ...
Creates a base class object (inheriting from nothing). Assigns new class object to name MyClass.
Since 2.5 the equivalent syntax class MyClass(): ... is allowed.
class MyClass (object): ...
Creates a new-style class
(inheriting from object makes a class a new-style class -available since Python 2.2-).
Assigns new class object to name MyClass.
class c (c_parent):
def __init__(self, name):
self.name = name
def print_name(self):
print "I'm", self.name
def call_parent(self):
c_parent.print_name(self)
instance = c('tom')
print instance.name
'tom'
instance.print_name()
"I'm tom"
self explicitly (see
call_parent in example above).int, float, str,
list, tuple, dict and file now (2.2) behave
like classes derived from base class object, and may be subclassed:New-style classes extendsx = int(2) # built-in cast function now a constructor for base type
y = 3 # <=> int(3) (litterals are instances of new base types)
print type(x), type(y) # int, int
assert isinstance(x, int) # replaces isinstance(x, types.IntType)
assert issubclass(int, object) # base types derive from base class 'object'.
s = "hello" # <=> str("hello")
assert isinstance(s, str)
f = 2.3 # <=> float(2.3)
class MyInt(int): pass # may subclass base types
x,y = MyInt(1), MyInt("2")
print x, y, x+y # => 1,2,3
class MyList(list): pass
l = MyList("hello")
print l # ['h', 'e', 'l', 'l', 'o']
object.
Old-style classes don't.
class C:
"A description of C"
def __init__(self):
"A description of the constructor"
# etc.
c.__doc__ == "A description of C".
c.__init__.__doc__ == "A description of the constructor"
next() returning the next element or
raising StopIteration.obj via the new built-in
function iter(obj), which calls obj.__class__.__iter__(). __iter__() and next().__iter__(); dictionaries (maps) enumerate their keys; files enumerates
their lines. list or a tuple from an
iterator, e.g. list(anIterator)for elt in
collection: if elt in collection:
x,y,z=
collection yield,
while return or raise StopIteration() are used to
notify the end of values. from __future__ import generators (not required since 2.3+) generator.next() to get the next
value until StopIteration is raised.
linkGenerator = (link for link in get_all_links() if not link.followed)
for link in linkGenerator:
...process link...
send(value). yield is now an expression
returning a value, so val = (yield i) will yield i to the caller, and will reciprocally
evaluate to the value "sent" back by the caller, or None.throw(type, value=None, traceback=None) is used to raise an exception inside the generator
(appears as raised by the yield expression).close() raises a new GeneratorExit exception inside the generator to terminate
the iteration. def genID(initialValue=0):
v = initialValue
while v < initialValue + 1000:
yield "ID_%05d" % v
v += 1
return # or: raise StopIteration()
generator = genID() # Create a generator
for i in range(10): # Generates 10 values
print generator.next()
__get__(self, obj, type=None) --> value__set__(self, obj, value) __delete__(self, obj)object).
)staticmethod(f)
to make method f(x) static (unbound).f = classmethod(f) to make method
f(theClass, x) a class method.property, which implements the descriptor protocol for attributes =>
Use propertyName = property(fget=None, fset=None,
fdel=None, doc=None) to define a property inside or outside
a class. Then access it as propertyName or
obj.propertyName__slots__ to constrain the list of assignable attribute names,
to avoid typos (which is normally not detected by Python and leads to the creation
of new attributes), e.g. __slots__ = ('x', 'y')@D
on the line preceding the function/method it decorates :
@D
def f(): ...
and is equivalent to:
def f(): ...
f = D(f)
@A
@B
@C
def f(): ...
is equivalent to:
f = A(B(C(f)))
@A
@B
@C(args)
def f(): ...
_deco = C(args)
f = A(B(_deco(f)))@staticmethod and @classmethod replace more elegantly
the equivalent declarations f = staticmethod(f) and f = classmethod(f).lambda [param_list]: returnedExprCreates an anonymous function.
returnedExpr must be an expression, not a statement (e.g., not "if xx:...", "print xxx", etc.) and thus can't contain newlines. Used mostly for filter(), map(), reduce() functions, and GUI callbacks.
List comprehensionsresult = [expression for item1 in sequence1 [if condition1]is equivalent to:
[for item2 in sequence2 ... for itemN in sequenceN]
]result = []
for item1 in sequence1:
for item2 in sequence2:
...
for itemN in sequenceN:
if (condition1) and further conditions:
result.append(expression)
Nested scopes
Since 2.2 nested scopes no longer need to be specially enabled by afrom __future__ import nested_scopesdirective, and are always used.
_builtin__ automatically imported.
| Function | Result |
|---|---|
| __import__(name[, globals[,locals[,from list]]]) | Imports module within the given context (see library reference for more details) |
| abs(x) | Returns the absolute value of the number x. |
| all(iterable) | Returns True if bool(x) is True for all values x in the iterable. |
| any(iterable) | Returns True if bool(x) is True for any value x in the iterable. |
| apply(f, args[, keywords]) | Calls func/method f with arguments args and optional keywords.
deprecated since 2.3,
replace apply(func, args, keywords) with func(*args, **keywords)
[details] |
| basestring() | Abstract superclass of str and unicode; can't be called or instantiated directly, but useful
in: isinstance(obj, basestring). |
| bool([x]) | Converts a value to a Boolean, using the standard truth testing procedure. If x is false or omitted,
returns False; otherwise returns True. bool is also a class/type, subclass
of int. Class bool cannot be subclassed further. Its only instances are
False and True. See also boolean operators |
| buffer(object[, offset[, size]]) | Returns a Buffer from a slice of object, which must support the buffer call interface
(string, array, buffer). Non essential function, see
[details] |
| callable(x) | Returns True if x callable, else False. |
| chr(i) | Returns one-character string whose ASCII code is integer i. |
| classmethod(function) | Returns a class method for function. A class method receives the class as implicit first argument,
just like an instance method receives the instance. To declare a class method, use this idiom:class C: Then call it on the class C.f() or on an instance C().f().
The instance is ignored except for its class. If a class method is called for a
derived class, the derived class object is passed as the implied first argument.Since 2.4 you can alternatively use the decorator notation: class C: |
| cmp(x,y) | Returns negative, 0, positive if x <, ==, > to y respectively. |
| coerce(x,y) | Returns a tuple of the two numeric arguments converted to a common type. Non essential function, see [details] |
| compile(string, filename, kind[, flags[, dont_inherit]]) | Compiles string into a code object. filename is used in error message, can be any string.
It is usually the file from which the code was read, or e.g. '<string>' if not read from file.
kind can be 'eval' if string is a single stmt, or 'single' which prints the output of
expression statements that evaluate to something else than None, or be 'exec'.
New args flags and dont_inherit concern future statements. |
| complex(real[, image]) | Creates a complex object (can also be done using J or j suffix, e.g. 1+3J). |
| delattr(obj, name) | Deletes the attribute named name of object obj <=> del obj.name |
| dict([mapping-or-sequence]) | Returns a new dictionary initialized from the optional argument (or an empty dictionary if no argument). Argument may be a sequence (or anything iterable) of pairs (key,value). |
| dir([object]) | Without args, returns the list of names in the current local symbol table. With a module, class or class instance object as arg, returns the list of names in its attr. dictionary. |
| divmod(a,b) | Returns tuple (a//b, a%b) |
| enumerate(iterable) | Iterator returning pairs (index, value) of iterable, e.g. List(enumerate('Py')) -> [(0, 'P'), (1, 'y')]. |
| eval(s[, globals[, locals]]) | Evaluates string s, representing a single python expression, in (optional) globals,
locals contexts. s must have no NUL's or newlines. s can also be a code object.
locals can be any mapping type, not only a regular Python dict. Example: x = 1; assert eval('x + 1') == 2
(To execute statements rather than a single expression, use Python statement exec or
built-in function execfile)
|
| execfile(file[, globals[,locals]]) | Executes a file without creating a new module, unlike import. locals can be any mapping type,
not only a regular Python dict. |
| file(filename[,mode[,bufsize]]) | Opens a file and returns a new file object. Alias for open. |
| filter(function,sequence) | Constructs a list from those elements of sequence for which function returns true. function takes one parameter. |
| float(x) | Converts a number or a string to floating point. |
| frozenset([iterable]) | Returns a frozenset (immutable set) object whose (immutable) elements are taken from iterable, or
empty by default. See also Sets. |
| getattr(object,name[,default])) | Gets attribute called name from object, e.g. getattr(x, 'f') <=> x.f).
If not found, raises AttributeError or returns default if specified. |
| globals() | Returns a dictionary containing the current global variables. |
| hasattr(object, name) | Returns true if object has an attribute called name. |
| hash(object) | Returns the hash value of the object (if it has one). |
| help([object]) | Invokes the built-in help system. No argument -> interactive help; if object is a string (name of a module, function, class, method, keyword, or documentation topic), a help page is printed on the console; otherwise a help page on object is generated. |
| hex(x) | Converts a number x to a hexadecimal string. |
| id(object) | Returns a unique integer identifier for object. Since 2.5 always returns non-negative numbers. |
| input([prompt]) | Prints prompt if given. Reads input and evaluates it. Uses line editing
/ history if module readline available. |
| int(x[, base]) | Converts a number or a string to a plain integer. Optional base parameter specifies base from which to convert string values. |
| intern(aString) | Enters aString in the table of interned strings and returns the string. Since 2.3, interned strings are no longer 'immortal' (never garbage collected), see [details] |
| isinstance(obj, classInfo) | Returns true if obj is an instance of class classInfo or an
object of type classInfo (classInfo may also be a tuple of classes or types).
If issubclass(A,B) then isinstance(x,A) => isinstance(x,B) |
| issubclass(class1, class2) | Returns true if class1 is derived from class2 (or if class1 is class2). |
| iter(obj[,sentinel]) | Returns an iterator on obj. If sentinel is absent, obj must be a collection
implementing either __iter__() or __getitem__(). If sentinel is given,
obj will be called with no arg; if the value returned is equal to sentinel,
StopIteration will be raised, otherwise the value will be returned.
See Iterators. |
| len(obj) | Returns the length (the number of items) of an object (sequence, dictionary, or instance of class implementing __len__). |
| list([seq]) | Creates an empty list or a list with same elements as seq. seq may be a sequence, a container that supports iteration, or an iterator object. If seq is already a list, returns a copy of it. |
| locals() | Returns a dictionary containing current local variables. |
| long(x[, base]) | Converts a number or a string to a long integer. Optional base parameter specifies the base from which to convert string values. |
| map(function, sequence[, sequence, ...]) | Returns a list of the results of applying function to each item from sequence(s).
If more than one sequence is given, the function is called with an argument list consisting of the
corresponding item of each sequence, substituting None for missing values when not all sequences have
the same length. If function is None, returns a list of the items of the sequence
(or a list of tuples if more than one sequence).
=> You might also consider using list comprehensions instead of map(). |
| max(iterable[, key=func]) max(v1, v2, ...[, key=func]) |
With a single argument iterable, returns the largest item of a non-empty iterable (such as a string, tuple or list). With more than one argument, returns the largest of the arguments. The optional key arg is a function that takes a single argument and is called for every value in the list. |
| min(iterable[, key=func]) min(v1, v2, ...[, key=func]) |
With a single argument iterable, returns the smallest item of a non-empty iterable (such as a string, tuple or list). With more than one argument, returns the smallest of the arguments. The optional key arg is a function that takes a single argument and is called for every value in the list. |
| object() | Returns a new featureless object. object is the base class for all new style classes,
its methods are common to all instances of new style classes. |
| oct(x) | Converts a number to an octal string. |
| open(filename [, mode='r', [bufsize]]) | Returns a new file object. See also alias file().
Use codecs.open()
instead to open an encoded file and provide transparent encoding / decoding.
|
| ord(c) | Returns integer ASCII value of c (a string of len 1). Works with Unicode char. |
| pow(x, y [, z]) | Returns x to power y [modulo z]. See also ** operator. |
| property([fget[, fset[, fdel[, doc]]]]) | Returns a property attribute for new-style classes (classes deriving from object).
fget, fset, and fdel are functions to get the property value, set the property value, and
delete the property, respectively. Typical use:
class C(object):
|
| range([start,] end [, step]) | Returns list of ints from >= start and < end. With 1 arg, list from 0..arg-1 With 2 args, list from start..end-1 With 3 args, list from start up to end by step |
| raw_input([prompt]) | Prints prompt if given, then reads string from std input (no trailing \n). See also input(). |
| reduce(f, list [, init]) | Applies the binary function f to the items of list so as to reduce the list to a single value. If init is given, it is "prepended" to list. |
| reload(module) | Re-parses and re-initializes an already imported module. Useful in interactive mode, if you want to reload a module after fixing it. If module was syntactically correct but had an error in initialization, must import it one more time before calling reload(). |
| repr(object) | Returns a string containing a printable and if possible evaluable representation of an object.
<=> `object` (using backquotes). Class redefinable (__repr__).
See also str() |
| round(x, n=0) | Returns the floating point value x rounded to n digits after the decimal point. |
| set([iterable]) | Returns a set object whose elements are taken from iterable, or
empty by default. See also Sets. |
| setattr(object, name, value) | This is the counterpart of getattr().setattr(o, 'foobar', 3) <=> o.foobar = 3. Creates attribute if it doesn't exist! |
| slice([start,] stop[, step]) | Returns a slice object representing a range, with R/O attributes: start, stop, step. |
| sorted(iterable[, cmp[, key[, reverse]]]) | Returns a new sorted list from the items in iterable. This contrasts with list.sort()
that sorts lists in place and doesn't apply to immutable sequences like strings or tuples.
See sequences.sort method. |
| staticmethod(function) | Returns a static method for function. A static method does not receive an implicit first argument.
To declare a static method, use this idiom:class C:Then call it on the class C.f() or on an instance C().f().
The instance is ignored except for its class.Since 2.4 you can alternatively use the decorator notation: class C: |
| str(object) | Returns a string containing a nicely printable representation of an object. Class overridable (__str__). See also repr(). |
| sum(iterable[, start=0]) | Returns the sum of a sequence of numbers (not strings), plus the value of parameter. Returns start when the sequence is empty. |
| super( type[, object-or-type]) | Returns the superclass of type. If the second argument is omitted the super object returned is unbound.
If the second argument is an object, isinstance(obj, type) must be true. If the second
argument is a type, issubclass(type2, type) must be true. Typical use:class C(B): |
| tuple([seq]) | Creates an empty tuple or a tuple with same elements as seq. seq may be a sequence, a container that supports iteration, or an iterator object. If seq is already a tuple, returns itself (not a copy). |
| type(obj) | Returns a type object [see module types] representing the type of obj. Example: import types if type(x) == types.StringType: print 'It is a string'. NB: it is better to use instead: if isinstance(x, types.StringType)... |
| unichr(code) | Returns a unicode string 1 char long with given code. |
| unicode(string[, encoding[,error]]]) | Creates a Unicode string from a 8-bit string, using the given encoding name and error treatment
('strict', 'ignore',or 'replace'}. For objects which provide a __unicode__()
method, it will call this method without arguments to create a Unicode string. |
| vars([object]) | Without arguments, returns a dictionary corresponding to the current local symbol table. With a module, class or class instance object as argument, returns a dictionary corresponding to the object's symbol table. Useful with the "%" string formatting operator. |
| xrange(start [, end [, step]]) | Like range(), but doesn't actually store entire list all at once. Good to use in "for" loops when there is a big range and little memory. |
| zip(seq1[, seq2,...]) | [No, that's not a compression tool! For that, see module zipfile] Returns a list of tuples where each tuple contains the nth element of each of the argument sequences.
Since 2.4 returns an empty list if called with no arguments (was raising
TypeError before). |
Exception before 2.5). New-style class. exception.args
is a tuple of the arguments passed to the constructor.KeyboardInterrupt & SystemExit were moved out of Exception because they
don't really represent errors, so now a try:...except Exception: will only catch errors, while a
try:...except: (or simply try:..except BaseException:) will still catch everything.Exception. sys.exit().
Before 2.5 was derived from Exception. Exception root class.
errno value. import to find module or name. BaseException. TypeError or more precise.
next() method to signal that there are no further values. BaseException. warning)
__init__.py). UnicodeDecodeError before 2.5). class C:
def __init__(self, v): self.value = v
def __add__(self, r): return self.value + r
a = C(3) # sort of like calling C.__init__(a, 3)
a + 4 # is equivalent to a.__add__(4)
| Method | Description |
|---|---|
| __new__(cls[, ...]) | Instance creation (on construction). If __new__ returns an instance of cls then __init__ is called with the rest of the arguments (...), otherwise __init__ is not invoked. More details here. |
| __init__(self, args) | Instance initialization (on construction) |
| __del__(self) | Called on object demise (refcount becomes 0) |
| __repr__(self) | repr() and `...` conversions |
| __str__(self) | str() and print statement |
| __cmp__(self,other) | Compares self to other and returns <0, 0, or >0. Implements >, <, == etc... |
| __index__(self) | [PEP357] Allows using any object as integer indice (e.g. for slicing). Must return a single integer or long integer value. |
| __lt__(self, other) | Called for self < other comparisons. Can return anything, or can raise an exception. |
| __le__(self, other) | Called for self <= other comparisons. Can return anything, or can raise an exception. |
| __gt__(self, other) | Called for self > other comparisons. Can return anything, or can raise an exception. |
| __ge__(self, other) | Called for self >= other comparisons. Can return anything, or can raise an exception. |
| __eq__(self, other) | Called for self == other comparisons. Can return anything, or can raise an exception. |
| __ne__(self, other) | Called for self != other (and self <> other) comparisons. Can return anything, or can raise an exception. |
| __hash__(self) | Compute a 32 bit hash code; hash() and dictionary ops.
Since 2.5 can also return a long integer, in which case the hash of
that value will be taken. |
| __nonzero__(self) | Returns 0 or 1 for truth value testing. when this method is not defined, __len__() is called
if defined; otherwise all class instances are considered "true". |
| __getattr__(self,name) | Called when attribute lookup doesn't find name. See also __getattribute__. |
| __getattribute__( self, name) | Same as __getattr__ but always called whenever the attribute name is accessed. |
| __setattr__(self, name, value) | Called when setting an attribute (inside, don't use "self.name = value", use instead "self.__dict__[name] = value") |
| __delattr__(self, name) | Called to delete attribute <name>. |
| __call__(self, *args, **kwargs) | Called when an instance is called as function: obj(arg1, arg2, ...) is a shorthand for
obj.__call__(arg1, arg2, ...). |
See list in the operator module. Operator function names are provided with 2 variants,
with or without leading & trailing '__' (e.g. __add__ or add).
| Operator | Special method |
|---|---|
| self + other | __add__(self, other) |
| self - other | __sub__(self, other) |
| self * other | __mul__(self, other) |
| self / other | __div__(self, other) or
__truediv__(self,other) if __future__.division is active. |
| self // other | __floordiv__(self, other) |
| self % other | __mod__(self, other) |
| divmod(self,other) | __divmod__(self, other) |
| self ** other | __pow__(self, other) |
| self & other | __and__(self, other) |
| self ^ other | __xor__(self, other) |
| self | other | __or__(self, other) |
| self << other | __lshift__(self, other) |
| self >> other | __rshift__(self, other) |
| nonzero(self) | __nonzero__(self) (used in boolean testing) |
| -self | __neg__(self) |
| +self | __pos__(self) |
| abs(self) | __abs__(self) |
| ~self | __invert__(self) (bitwise) |
| self += other | __iadd__(self, other) |
| self -= other | __isub__(self, other) |
| self *= other | __imul__(self, other) |
| self /= other | __idiv__(self, other) or
__itruediv__(self,other) if __future__.division is in effect. |
| self //= other | __ifloordiv__(self, other) |
| self %= other | __imod__(self, other) |
| self **= other | __ipow__(self, other) |
| self &= other | __iand__(self, other) |
| self ^= other | __ixor__(self, other) |
| self |= other | __ior__(self, other) |
| self <<= other | __ilshift__(self, other) |
| self >>= other | __irshift__(self, other) |
| built-in function | Special method |
|---|---|
| int(self) | __int__(self) |
| long(self) | __long__(self) |
| float(self) | __float__(self) |
| complex(self) | __complex__(self) |
| oct(self) | __oct__(self) |
| hex(self) | __hex__(self) |
| coerce(self, other) | __coerce__(self, other) |
__add__(a, 3) __radd__(a, 3) | Operation | Special method | Notes | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| All sequences and maps : | |||||||||||||||||||
| len(self) | __len__(self) | length of object, >= 0. Length 0 == false | |||||||||||||||||
| self[k] | __getitem__(self, k) | Get element at indice /key k (indice starts at 0). Or, if k is a slice object, return a slice. | |||||||||||||||||
| __missing__(self, key) | Hook called when key is not found in the dictionary, returns the default value. | ||||||||||||||||||
| self[k] = value | __setitem__(self, k, value) | Set element at indice/key/slice k. | |||||||||||||||||
| del self[k] | __delitem__(self, k) | Delete element at indice/key/slice k. | |||||||||||||||||
| elt in self elt not in self |
__contains__(self, elt) not __contains__(self, elt) |
More efficient than std iteration thru sequence. | |||||||||||||||||
| iter(self) | __iter__(self) | Returns an iterator on elements (keys for mappings <=> self.iterkeys()). See iterators. | |||||||||||||||||
| Sequences, general methods, plus: | |||||||||||||||||||
| self[i:j] | __getslice__(self, i, j) | Deprecated since 2.0, replaced by __getitem__ with a slice object as parameter. |
|||||||||||||||||
| self[i:j] = seq | __setslice__(self, i, j,seq) | Deprecated since 2.0, replaced by __setitem__ with a slice object as parameter. |
|||||||||||||||||
| del self[i:j] | __delslice__(self, i, j) | Same as self[i:j] = [] - Deprecated since 2.0, replaced by __delitem__ with a
slice object as parameter. |
|||||||||||||||||
| self * n | __mul__(self, n) | (__repeat__ in the official doc but doesn't work!) | |||||||||||||||||
| self + other | __add__(self, other) | (__concat__ in the official doc but doesn't work!) | |||||||||||||||||
| Mappings, general methods, plus: | |||||||||||||||||||
| hash(self) | __hash__(self) | hashed value of object self is used for dictionary keys | |||||||||||||||||
| Attribute | Meaning |
|---|---|
| |
dir() instead |
| Attribute | Meaning |
|---|---|
| __doc__ | (string/None, R/O): doc string (<=> __dict__['__doc__']) |
| __name__ | (string, R/O): module name (also in __dict__['__name__']) |
| __dict__ | (dict, R/O): module's name space |
| __file__ | (string/undefined, R/O): pathname of .pyc, .pyo or .pyd (undef for modules statically linked to the interpreter).
Before 2.3 use sys.argv[0] instead to find the current script filename.
|
| __path__ | (list/undefined, R/W): List of directory paths where to find the package (for packages only). |
| Attribute | Meaning |
|---|---|
| __doc__ | (string/None, R/W): doc string (<=> __dict__['__doc__']) |
| __name__ | (string, R/W): class name (also in __dict__['__name__']) |
| __module__ | (string, R/W): module name in which the class was defined |
| __bases__ | (tuple, R/W): parent classes |
| __dict__ | (dict, R/W): attributes (class name space) |
| Attribute | Meaning |
|---|---|
| __class__ | (class, R/W): instance's class |
| __dict__ | (dict, R/W): attributes |
| Attribute | Meaning |
|---|---|
| __doc__ | (string/None, R/W): doc string |
| __name__ | (string, R/O): function name |
| func_doc | (R/W): same as __doc__ |
| func_name | (R/O, R/W from 2.4): same as __name__ |
| func_defaults | (tuple/None, R/W): default args values if any |
| func_code | (code, R/W): code object representing the compiled function body |
| func_globals | (dict, R/O): ref to dictionary of func global variables |
| Attribute | Meaning |
|---|---|
| __doc__ | (string/None, R/O): doc string |
| __name__ | (string, R/O): method name (same as im_func.__name__) |
| im_class | (class, R/O): class defining the method (may be a base class) |
| im_self | (instance/None, R/O): target instance object (None if unbound) |
| im_func | (function, R/O): function object |
| Attribute | Meaning |
|---|---|
| __doc__ | (string/None, R/O): doc string |
| __name__ | (string, R/O): function name |
| __self__ | [methods only] target object |
| |
dir() instead. |
| Attribute | Meaning |
|---|---|
| co_name | (string, R/O): function name |
| co_argcount | (int, R/0): number of positional args |
| co_nlocals | (int, R/O): number of local vars (including args) |
| co_varnames | (tuple, R/O): names of local vars (starting with args) |
| co_code | (string, R/O): sequence of bytecode instructions |
| co_consts | (tuple, R/O): literals used by the bytecode, 1st one is function doc (or None) |
| co_names | (tuple, R/O): names used by the bytecode |
| co_filename | (string, R/O): filename from which the code was compiled |
| co_firstlineno | (int, R/O): first line number of the function |
| co_lnotab | (string, R/O): string encoding bytecode offsets to line numbers. |
| co_stacksize | (int, R/O): required stack size (including local vars) |
| co_flags | (int, R/O): flags for the interpreter bit 2 set if fct uses "*arg" syntax, bit 3 set if fct uses '**keywords' syntax |
| Attribute | Meaning |
|---|---|
| f_back | (frame/None, R/O): previous stack frame (toward the caller) |
| f_code | (code, R/O): code object being executed in this frame |
| f_locals | (dict, R/O): local vars |
| f_globals | (dict, R/O): global vars |
| f_builtins | (dict, R/O): built-in (intrinsic) names |
| f_restricted | (int, R/O): flag indicating whether fct is executed in restricted mode |
| f_lineno | (int, R/O): current line number |
| f_lasti | (int, R/O): precise instruction (index into bytecode) |
| f_trace | (function/None, R/W): debug hook called at start of each source line |
| f_exc_type | (Type/None, R/W): Most recent exception type |
| f_exc_value | (any, R/W): Most recent exception value |
| f_exc_traceback | (traceback/None, R/W): Most recent exception traceback |
| Attribute | Meaning |
|---|---|
| tb_next | (frame/None, R/O): next level in stack trace (toward the frame where the exception occurred) |
| tb_frame | (frame, R/O): execution frame of the current level |
| tb_lineno | (int, R/O): line number where the exception occured |
| tb_lasti | (int, R/O): precise instruction (index into bytecode) |
| Attribute | Meaning |
|---|---|
| start | (any/None, R/O): lowerbound, included |
| stop | (any/None, R/O): upperbound, excluded |
| step | (any/None, R/O): step value |
| Attribute | Meaning |
|---|---|
| real | (float, R/O): real part |
| imag | (float, R/O): imaginary part |
| Attribute | Meaning |
|---|---|
| tolist | (Built-in method, R/O): ? |
| Variable | Content |
|---|---|
| argv | The list of command line arguments passed to a Python script. sys.argv[0] is the script name. |
| builtin_module_names | A list of strings giving the names of all modules written in C that are linked into this interpreter. |
| byteorder | Native byte order, either 'big'(-endian) or 'little'(-endian). |
| check_interval | How often to check for thread switches or signals (measured in number of virtual machine instructions) |
| copyright | A string containing the copyright pertaining to the Python interpreter. |
| exec_prefix prefix |
Root directory where platform-dependent Python files are installed, e.g. 'C:\\Python23', '/usr'. |
| executable | Name of executable binary of the Python interpreter (e.g. 'C:\\Python23\\python.exe', '/usr/bin/python') |
| exitfunc | User can set to a parameterless function. It will get called before interpreter exits.
Deprecated since 2.4. Code should be using the existing
atexit module |
| last_type, last_value, last_traceback | Set only when an exception not handled and interpreter prints an error. Used by debuggers. |
| maxint | Maximum positive value for integers. Since 2.2 integers and long integers are unified, thus integers have no limit. |
| maxunicode | Largest supported code point for a Unicode character. |
| modules | Dictionary of modules that have already been loaded. |
| path | Search path for external modules. Can be modified by program.
sys.path[0] == directory of script currently executed. |
| platform | The current platform, e.g. "sunos5", "win32" |
| ps1, ps2 | Prompts to use in interactive mode, normally ">>>" and "..." |
| stdin, stdout, stderr | File objects used for I/O. One can redirect by assigning a new file object
to them (or any object: with a method write(string)
for stdout/stderr, or with a method readline() for stdin).
__stdin__,__stdout__ and __stderr__ are the default values. |
| subversion | Info about Python build version in the Subversion repository: tuple (interpreter-name, branch-name,
revision-range), e.g. ('CPython', 'tags/r25', '51908'). |
| version | String containing version info about Python interpreter. |
| version_info | Tuple containing Python version info - (major, minor, micro, level, serial). |
| winver | Version number used to form registry keys on Windows platforms (e.g. '2.2'). |
| Variable | Meaning |
|---|---|
| name | name of O/S-specific module (e.g. "posix", "mac", "nt") |
| path | O/S-specific module for path manipulations. On Unix, os.path.split() <=> posixpath.split() |
| curdir | string used to represent current directory (eg '.') |
| pardir | string used to represent parent directory (eg '..') |
| sep | string used to separate directories ('/' or '\').
Tip: Use os.path.join() to build portable paths. |
| altsep | Alternate separator if applicable (None otherwise) |
| pathsep | character used to separate search path components (as in $PATH), eg. ';' for windows. |
| linesep | line separator as used in text files, ie '\n' on Unix, '\r\n' on Dos/Win, '\r' on Mac. |
| Function | Result |
|---|---|
| makedirs(path[, mode=0777]) | Recursive directory creation (create required intermediary dirs); os.error if fails. |
| removedirs(path) | Recursive directory delete (delete intermediary empty dirs);
fails (os.error) if the directories are not empty. |
| renames(old, new) | Recursive directory or file renaming; os.error if fails. |
| urandom(n) | Returns a string containing n bytes of random data. |
| Variable | Meaning |
|---|---|
| environ | dictionary of environment variables, e.g. posix.environ['HOME']. |
| error | exception raised on POSIX-related error. Corresponding value is tuple of errno code and perror() string. |
| Function | Result |
|---|---|
| chdir(path) | Changes current directory to path. |
| chmod(path, mode) | Changes the mode of path to the numeric mode |
| close(fd) | Closes file descriptor fd opened with posix.open. |
| _exit(n) | Immediate exit, with no cleanups, no SystemExit, etc... Should use this to exit a child process. |
| execv(p, args) | "Become" executable p with args args |
| getcwd() | Returns a string representing the current working directory. |
| getcwdu() | Returns a Unicode string representing the current working directory. |
| getpid() | Returns the current process id. |
| getsid() | Calls the system call getsid() [Unix]. |
| fork() | Like C's fork(). Returns 0 to child, child pid to parent [Not on Windows]. |
| kill(pid, signal) | Like C's kill [Not on Windows]. |
| listdir(path) | Lists (base)names of entries in directory path, excluding '.' and '..'. If path is a Unicode string, so will be the returned strings. |
| lseek(fd, pos, how) | Sets current position in file fd to position pos, expressed as an offset relative to beginning of file (how=0), to current position (how=1), or to end of file (how=2). |
| mkdir(path[, mode]) | Creates a directory named path with numeric mode (default 0777). |
| open(file, flags, mode) | Like C's open(). Returns file descriptor. Use file object functions rather than this low level ones. |
| pipe() | Creates a pipe. Returns pair of file descriptors (r, w) [Not on Windows]. |
| popen(command, mode='r', bufSize=0) | Opens a pipe to or from command. Result is a file object to read to or write from, as indicated by mode being 'r' or 'w'. Use it to catch a command output ('r' mode), or to feed it ('w' mode). |
| remove(path) | See unlink. |
| rename(old, new) | Renames/moves the file or directory old to new. [error if target name already exists] |
| renames(old, new) | Recursive directory or file renaming function. Works like rename(), except creation of any intermediate directories needed to make the new pathname good is attempted first. After the rename, directories corresponding to rightmost path segments of the old name will be pruned away using removedirs(). |
| rmdir(path) | Removes the empty directory path |
| read(fd, n) | Reads n bytes from file descriptor fd and return as string. |
| stat(path) | Returns st_mode, st_ino, st_dev, st_nlink, st_uid,st_gid, st_size, st_atime, st_mtime, st_ctime. [st_ino, st_uid, st_gid are dummy on Windows] |
| system(command) | Executes string command in a subshell. Returns exit status of subshell (usually 0 means OK). Since 2.4 use subprocess.call() instead. |
| times() | Returns accumulated CPU times in sec (user, system, children's user, children's sys, elapsed real time) [3 last not on Windows]. |
| unlink(path) | Unlinks ("deletes") the file (not dir!) path. Same as: remove. |
| utime(path, (aTime, mTime)) | Sets the access & modified time of the file to the given tuple of values. |
| wait() | Waits for child process completion. Returns tuple of pid, exit_status [Not on Windows]. |
| waitpid(pid, options) | Waits for process pid to complete. Returns tuple of pid, exit_status [Not on Windows]. |
| walk(top[, topdown=True [, onerror=None]]) | Generates a list of file names in a directory tree, by walking the tree either top down or bottom up.
For each directory in the tree rooted at directory top (including top itself), it yields a
3-tuple (dirpath, dirnames, filenames) - more info here.
See also os.path.walk(). |
| write(fd, str) | Writes str to file fd. Returns nb of bytes written. |
os.path.exists(p))!| Function | Result |
|---|---|
| abspath(p) | Returns absolute path for path p, taking current working dir in account. |
| commonprefix(list) | Returns the longuest path prefix (taken character-by-character) that is a prefix of all paths in list (or '' if list empty). |
| dirname/basename(p) | directory and name parts of the path p. See also split. |
| exists(p) | True if string p is an existing path (file or directory).
See also lexists. |
| expanduser(p) | Returns string that is (a copy of) p with "~" expansion done. |
| expandvars(p) | Returns string that is (a copy of) p with environment vars expanded. [Windows: case significant; must use Unix: $var notation, not %var%] |
| getmtime(filepath) | Returns last modification time of filepath (integer nb of seconds since epoch). |
| getatime(filepath) | Returns last access time of filepath (integer nb of seconds since epoch). |
| getsize(filepath) | Returns the size in bytes of filepath. os.error if file inexistent or inaccessible. |
| isabs(p) | True if string p is an absolute path. |
| isdir(p) | True if string p is a directory. |
| islink(p) | True if string p is a symbolic link. |
| ismount(p) | True if string p is a mount point [true for all dirs on Windows]. |
| join(p[,q[,...]]) | Joins one or more path components in a way suitable for the current OS. |
| lexists(path) | True if the file specified by path exists, whether or not it's a symbolic link (unlike exists). |
| split(p) | Splits p into (head, tail) where tail is last pathname component and
head is everything leading up to that. <=> (dirname(p), basename(p)) |
| splitdrive(p) | Splits path p in a pair ('drive:', tail) [Windows] |
| splitext(p) | Splits into (root, ext) where last comp of root contains no periods and ext is empty or starts with a period. |
| walk(p, visit, arg) | Calls the function visit with arguments (arg, dirname, names)
for each directory recursively in the directory tree rooted at p (including
p itself if it's a dir). The argument dirname specifies the visited directory,
the argument names lists the files in the directory. The visit function may
modify names to influence the set of directories visited below dirname, e.g.
to avoid visiting certain parts of the tree. See also os.walk() for an alternative. |
| Function | Result |
|---|---|
| copy(src, dest) | Copies the contents of file src to file dest, retaining file permissions. |
| copytree(src, dest[, symlinks]) | Recursively copies an entire directory tree rooted at src into dest (which should not already exist). If symlinks is true, links in src are kept as such in dest. |
| move(src, dest) | Recursively moves a file or directory to a new location. |
| rmtree(path[, ignore_errors[, onerror]]) | Deletes an entire directory tree, ignoring errors if ignore_errors is true, or calling onerror(func, path, sys.exc_info()) if supplied, with arguments func (faulty function), and path (concerned file). This fct fails when the files are Read Only. |
| Variable | Meaning |
|---|---|
| altzone | Signed offset of local DST timezone in sec west of the 0th meridian. |
| daylight | Non zero if a DST timezone is specified. |
| timezone | The offset of the local (non-DST) timezone, in seconds west of UTC. |
| tzname | A tuple (name of local non-DST timezone, name of local DST timezone). |
| Function | Result | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| clock() | On Unix: current processor time as a floating point number expressed in seconds. On Windows: wall-clock seconds elapsed since the 1st call to this function, as a floating point number (precision < 1µs). |
||||||||||||||||||||||||||||||
| time() | Returns a float representing UTC time in seconds since the epoch. | ||||||||||||||||||||||||||||||
| gmtime([secs]), localtime([secs]) |
Returns a 9-tuple representing time. Current time is used if secs is not provided. Since 2.2, returns a struct_time object (still accessible as a tuple) with
the following attributes:
|
||||||||||||||||||||||||||||||
| asctime([timeTuple]), | 24-character string of the following form: 'Mon Apr 03 08:31:14 2006'. Current time is used if secs is not provided. | ||||||||||||||||||||||||||||||
| ctime([secs]) | equivalent to asctime(localtime(secs)) |
||||||||||||||||||||||||||||||
| mktime(timeTuple) | Inverse of localtime(). Returns a float representing a number of seconds. |
||||||||||||||||||||||||||||||
| strftime(format[, timeTuple]) | Formats a time tuple as a string, according to format (see table below). Current time is used if secs is not provided. | ||||||||||||||||||||||||||||||
| strptime(string[, format]) | Parses a string representing a time according to format (same format as for
strftime(), see below), default "%a %b %d %H:%M:%S %Y" = asctime format.Returns a time tuple/ struct_time. |
||||||||||||||||||||||||||||||
| sleep(secs) | Suspends execution for secs seconds. secs can be a float. |
| Directive | Meaning |
|---|---|
%a |
Locale's abbreviated weekday name. |
%A |
Locale's full weekday name. |
%b |
Locale's abbreviated month name. |
%B |
Locale's full month name. |
%c |
Locale's appropriate date and time representation. |
%d |
Day of the month as a decimal number [01,31]. |
%H |
Hour (24-hour clock) as a decimal number [00,23]. |
%I |
Hour (12-hour clock) as a decimal number [01,12]. |
%j |
Day of the year as a decimal number [001,366]. |
%m |
Month as a decimal number [01,12]. |
%M |
Minute as a decimal number [00,59]. |
%p |
Locale's equivalent of either AM or PM. |
%S |
Second as a decimal number [00,61]. Yes, 61 ! |
%U |
Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0. |
%w |
Weekday as a decimal number [0(Sunday),6]. |
%W |
Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0. |
%x |
Locale's appropriate date representation. |
%X |
Locale's appropriate time representation. |
%y |
Year without century as a decimal number [00,99]. |
%Y |
Year with century as a decimal number. |
%Z |
Time zone name (or by no characters if no time zone exists). |
%% |
A literal "%" character. |
| Variable | Meaning |
|---|---|
| digits | The string '0123456789'. |
| hexdigits, octdigits | Legal hexadecimal & octal digits. |
| letters, uppercase, lowercase, whitespace | Strings containing the appropriate characters. |
| ascii_letters, ascii_lowercase, ascii_uppercase | Same, taking the current locale in account. |
| index_error | Exception raised by index() if substring not found. |
| Function | Result |
|---|---|
| expandtabs(s, tabSize) | Returns a copy of string s with tabs expanded. |
| find/rfind(s, sub[, start=0[, end=0]) | Returns the lowest/highest index in s where the substring sub is found such that sub is wholly contained in s[start:end]. Return -1 if sub not found. |
| ljust/rjust/center(s, width[, fillChar=' ']) | Returns a copy of string s; left/right justified/centered in a field of given width, padded with spaces or the given character. s is never truncated. |
| lower/upper(s) | Returns a string that is (a copy of) s in lowercase/uppercase. |
| split(s[, sep=whitespace[, maxsplit=0]]) | Returns a list containing the words of the string s, using the string sep as a separator. |
| rsplit(s[, sep=whitespace[, maxsplit=0]]) | Same as split above but starts splitting from the end of string, e.g.
'A,B,C'.split(',', 1) == ['A', 'B,C'] but 'A,B,C'.rsplit(',', 1) == ['A,B', 'C'] |
| join(words[, sep=' ']) | Concatenates a list or tuple of words with intervening separators; inverse of split. |
| replace(s, old, new[, maxsplit=0] | Returns a copy of string s with all occurrences of substring old replaced by new. Limits to maxsplit first substitutions if specified. |
| strip(s[, chars=None]) | Returns a string that is (a copy of) s without leading and trailing chars
(default: whitespace), if any. Also: lstrip, rstrip. |
r'\w*')
to literalize backslashes. | Form | Description |
|---|---|
| . | Matches any character (including newline if DOTALL flag specified). |
| ^ | Matches start of the string (of every line in MULTILINE mode). |
| $ | Matches end of the string (of every line in MULTILINE mode). |
| * | 0 or more of preceding regular expression (as many as possible). |
| + | 1 or more of preceding regular expression (as many as possible). |
| ? | 0 or 1 occurrence of preceding regular expression. |
| *?, +?, ?? | Same as *, + and ? but matches as few characters as possible. |
| {m,n} | Matches from m to n repetitions of preceding RE. |
| {m,n}? | Idem, attempting to match as few repetitions as possible. |
| [ ] | Defines character set: e.g. '[a-zA-Z]' to match all letters (see also \w \S). |
| [^ ] | Defines complemented character set: matches if char is NOT in set. |
| \ | Escapes special chars '*?+&$|()' and introduces special sequences (see below). Due to Python string rules, write as '\\' or r'\' in the pattern string. |
| \\ | Matches a litteral '\'; due to Python string rules, write as '\\\\' in pattern string, or better using raw string: r'\\'. |
| | | Specifies alternative: 'foo|bar' matches 'foo' or 'bar'. |
| (...) | Matches any RE inside (), and delimits a group. |
| (?:...) | Idem but doesn't delimit a group (non capturing parenthesis). |
| (?P<name>...) | Matches any RE inside (), and delimits a named group, (e.g. r'(?P<id>[a-zA-Z_]\w*)' defines a group named id). |
| (?P=name) | Matches whatever text was matched by the earlier group named name. |
| (?=...) | Matches if ... matches next, but doesn't consume any of the string e.g. 'Isaac (?=Asimov)' matches 'Isaac' only if followed by 'Asimov'. |
| (?!...) | Matches if ... doesn't match next. Negative of (?=...). |
| (?<=...) | Matches if the current position in the string is preceded by a match for ... that ends at the current position. This is called a positive lookbehind assertion. |
| (?<!...) | Matches if the current position in the string is not preceded by a match for .... This is called a negative lookbehind assertion. |
| (?(group)A|B) | [2.4+] group is either a numeric group ID or a group name defined with (?Pgroup...)
earlier in the expression. If the specified group matched, the regular expression pattern A
will be tested against the string; if the group didn't match, the pattern B will be used instead. |
| (?#...) | A comment; ignored. |
| (?letters) | letters is one or more of 'i','L', 'm', 's', 'u', 'x'. Sets the
corresponding flags (re.I, re.L, re.M, re.S, re.U, re.X) for the
entire RE. See the compile() function for equivalent flags. |
| Sequence | Description |
|---|---|
| \number | Matches content of the group of the same number; groups are numbered starting from 1. |
| \A | Matches only at the start of the string. |
| \b | Empty str at beginning or end of word: '\bis\b' matches 'is', but not 'his'. |
| \B | Empty str NOT at beginning or end of word. |
| \d | Any decimal digit (<=> [0-9]). |
| \D | Any non-decimal digit char (<=> [^0-9]). |
| \s | Any whitespace char (<=> [ \t\n\r\f\v]). |
| \S | Any non-whitespace char (<=> [^ \t\n\r\f\v]). |
| \w | Any alphaNumeric char (depends on LOCALE flag). |
| \W | Any non-alphaNumeric char (depends on LOCALE flag). |
| \Z | Matches only at the end of the string. |
| Variable | Meaning |
|---|---|
| error | Exception when pattern string isn't a valid regexp. |
| Function | Result |
|---|---|
| compile(pattern[,flags=0]) | Compiles a RE pattern string into a regular expression object. Flags (combinable by |):
|
| escape(string) | Returns (a copy of) string with all non-alphanumerics backslashed. |
| match(pattern, string[, flags]) | If 0 or more chars at beginning of string matches the RE pattern string,
returns a corresponding MatchObject instance,
or None if no match. |
| search(pattern, string[, flags]) | Scans thru string for a location matching pattern, returns a corresponding
MatchObject instance, or None if no match. |
| split(pattern, string[, maxsplit=0]) | Splits string by occurrences of pattern. If capturing () are used in pattern, then occurrences of patterns or subpatterns are also returned. |
| findall(pattern, string) | Returns a list of non-overlapping matches in pattern, either a list of groups or a list of tuples if the pattern has more than 1 group. |
| sub(pattern, repl, string[, count=0]) | Returns string obtained by replacing the (count first) leftmost non-overlapping occurrences of pattern (a string or a RE object) in string by repl; repl can be a string or a function called with a single MatchObj arg, which must return the replacement string. |
| subn(pattern, repl, string[, count=0]) | Same as sub(), but returns a tuple (newString, numberOfSubsMade). |
| Attribute | Description |
|---|---|
| flags | Flags arg used when RE obj was compiled, or 0 if none provided. |
| groupindex | Dictionary of {group name: group number} in pattern. |
| pattern | Pattern string from which RE obj was compiled. |
| Method | Result |
|---|---|
| match(string[, pos][, endpos]) | If zero or more characters at the beginning of string match this regular expression,
returns a corresponding MatchObject instance. Returns None if
the string does not match the pattern; note that this is different from a zero-length match.The optional second parameter pos gives an index in the string where the search is to start; it defaults to 0. This is not completely equivalent to slicing the string; the '' pattern character matches at the real beginning of the string and at positions just after a newline, but not necessarily at the index where the search is to start. The optional parameter endpos limits how far the string will be searched; it will be as if the string is endpos characters long, so only the characters from pos to endpos will be searched for a match. |
| search(string[, pos][, endpos]) | Scans through string looking for a location where this regular expression produces a match,
and returns a corresponding MatchObject instance. Returns None if
no position in the string matches the pattern; note that this is different from finding a
zero-length match at some point in the string.The optional pos and endpos parameters have the same meaning as for the match() method. |
| split(string[, maxsplit=0]) | Identical to the split() function, using the compiled pattern. |
| findall(string) | Identical to the findall() function, using the compiled pattern. |
| sub(repl, string[, count=0]) | Identical to the sub() function, using the compiled pattern. |
| subn(repl, string[, count=0]) | Identical to the subn() function, using the compiled pattern. |
| Attribute | Description |
|---|---|
| pos | Value of pos passed to search or match functions; index into string at which RE engine started search. |
| endpos | Value of endpos passed to search or match functions; index into string beyond which RE engine won't go. |
| re | RE object whose match or search fct produced this MatchObj instance. |
| string | String passed to match() or search(). |
| Function | Result |
|---|---|
| group([g1, g2, ...]) | Returns one or more groups of the match. If one arg, result is a string; if multiple args, result is a tuple with one item per arg. If gi is 0, returns value is entire matching string; if 1 <= gi <= 99, return string matching group #gi (or None if no such group); gi may also be a group name. |
| groups() | Returns a tuple of all groups of the match; groups not participating to the match have a value of None. Returns a string instead of tuple if len(tuple)== 1. |
| start(group), end(group) | Returns indices of start & end of substring matched by group (or None if group exists but didn't contribute to the match). |
| span(group) | Returns the 2-tuple (start(group), end(group)); can be (None, None) if group didn't contibute to the match. |
| Name | Value |
|---|---|
| pi | 3.1415926535897931 |
| e | 2.7182818284590451 |
| Name | Result |
|---|---|
| acos(x) | Returns the arc cosine (measured in radians) of x. |
| asin(x) | Returns the arc sine (measured in radians) of x. |
| atan(x) | Returns the arc tangent (measured in radians) of x. |
| atan2(y, x) | Returns the arc tangent (measured in radians) of y/x. The result is between -pi and pi.
Unlike atan(y/x), the signs of both x and y are considered. |
| ceil(x) | Returns the ceiling of x as a float. This is the smallest integral value >= x. |
| cos(x) | Returns the cosine of x (measured in radians). |
| cosh(x) | Returns the hyperbolic cosine of x. |
| degrees(x) | Converts angle x from radians to degrees. |
| exp(x) | Returns e raised to the power of x. |
| fabs(x) | Returns the absolute value of the float x. |
| floor(x) | Returns the floor of x as a float. This is the largest integral value <= x. |
| fmod(x, y) | Returns fmod(x, y), according to platform C. x % y may differ. |
| frexp(x) | Returns the mantissa and exponent of x, as pair (m, e).
m is a float and e is an int, such that x = m * 2.**e. If x is 0, m and e
are both 0. Else 0.5 <= abs(m) < 1.0. |
| hypot(x, y) | Returns the Euclidean distance sqrt(x*x + y*y). |
| ldexp(x, i) | x * (2**i) |
| log(x[, base]) | Returns the logarithm of x to the given base. If the base is not specified, returns the natural logarithm (base e) of x. |
| log10(x) | Returns the base 10 logarithm of x. |
| modf(x) | Returns the fractional and integer parts of x. Both results carry the sign of x. The integer part is returned as a float. |
| pow(x, y) | Returns x**y (x to the power of y).
Note that for y=2, it is more efficient to use x*x. |
| radians(x) | Converts angle x from degrees to radians. |
| sin(x) | Returns the sine (measured in radians) of x. |
| sinh(x) | Returns the hyperbolic sine of x. |
| sqrt(x) | Returns the square root of x. |
| tan(x) | Returns the tangent (measured in radians) of x. |
| tanh(x) | Returns the hyperbolic tangent of x. |
getopt(list, optstr) -- Similar to C. <optstr> is option letters to look for.
Put ':' after letter if option takes arg. E.g.
# invocation was "python test.py -c hi -a arg1 arg2"
opts, args = getopt.getopt(sys.argv[1:], 'ab:c:')
# opts would be
[('-c', 'hi'), ('-a', '')]
# args would be
['arg1', 'arg2']
Lib directory. The subdirectory
Lib/site-packages contains platform-specific packages and modules. | Operation | Result |
|---|---|
| __builtin__ | Provide direct access to all `built-in' identifiers of Python, e.g.
__builtin__.open is the full name for the built-in function open(). |
| __future__ | Future statement definitions. Used to progressively introduce new features in the language. |
| __main__ | Represent the (otherwise anonymous) scope in which the interpreter's main program executes --
commands read either from standard input, from a script file, or from an interactive prompt.
Typical idiom to check if a code was run as a script (as opposed to being imported): |
| aifc | Stuff to parse AIFF-C and AIFF files. |
| anydbm | Generic interface to all dbm clones. (dbhash, gdbm, dbm, dumbdbm). |
| asynchat | A class supporting chat-style (command/response) protocols. |
| asyncore | Basic infrastructure for asynchronous socket service clients and servers. |
| atexit | Register functions to be called at exit of Python interpreter. |
| audiodev | Classes for manipulating audio devices (currently only for Sun and SGI). |
| audioop | Manipulate raw audio data. 2.5: Supports the a-LAW encoding. |
| base64 | Conversions to/from base64 transport encoding as per RFC-1521. |
| BaseHTTPServer | HTTP server base class |
| |
|
| bdb | A generic Python debugger base class. |
| binascii | Convert between binary and ASCII. |
| binhex | Macintosh binhex compression/decompression. |
| bisect | Bisection algorithms. |
| bsddb | (Optional) improved BSD database interface [package]. |
| bz2 | BZ2 compression. |
| calendar | Calendar printing functions. |
| cgi | Wraps the WWW Forms Common Gateway Interface (CGI). |
| CGIHTTPServer | CGI-savvy HTTP Server. |
| cgitb | Traceback manager for CGI scripts. |
| chunk | Read IFF chunked data. |
| cmath | Mathematical functions for complex numbers. See also math. |
| cmd | A generic class to build line-oriented command interpreters. |
| |
|
| |
|
| code | Utilities needed to emulate Python's interactive interpreter. |
| codecs | Lookup existing Unicode encodings and register new ones. 2.5: support for incremental codecs. |
| codeop | Utilities to compile possibly incomplete Python source code. |
| collections | high-performance container datatypes. Currently, the only datatype is a double-ended queue.
2.5: Type deque has now a remove method.
New type defaultdict. |
| colorsys | Conversion functions between RGB and other color systems. |
| commands | Execute shell commands via os.popen [Unix]. |
| compileall | Force "compilation" of all .py files in a directory. |
| ConfigParser | Configuration file parser (much like windows .ini files). |
| Cookie | HTTP state (cookies) management. |
| copy | Generic shallow and deep copying operations. |
| copy_reg | Helper to provide extensibility for modules pickle/cPickle. |
| cPickle | Faster, C implementation of pickle. |
| cProfile | Faster, C implementation of profile. |
| crypt | Function to check Unix passwords [Unix]. |
| cStringIO | Faster, C implementation of StringIO. |
| csv | Tools to read comma-separated files (of variations thereof). 2.5: Several enhancements. |
| ctypes | "Foreign function" library for Python. Provides C compatible data types, and allows to call functions in dlls/shared libraries. Can be used to wrap these libraries in pure Python. |
| curses | Terminal handling for character-cell displays [Unix/OS2/DOS only]. |
| datetime | Improved date/time types (date, time, datetime, timedelta).
2.5: New method strptime(string, format) for class datetime. |
| dbhash | (g)dbm-compatible interface to bsdhash.hashopen. |
| decimal | Decimal floating point arithmetic. |
| difflib | Tool for comparing sequences, and computing the changes required to convert one into another.
2.5: Improved SequenceMatcher.get_matching_blocks() method . |
| dircache | Sorted list of files in a dir, using a cache. |
| |
|
| dis | Bytecode disassembler. |
| distutils | Package installation system. 2.5: Function setup enhanced
with new keyword parameters requires, provides, obsoletes, and
download_url [PEP314]. |
| distutils.command.register | Registers a module in the Python package index (PyPI). This command plugin adds the register command to distutil scripts. |
| distutils.debug | |
| distutils.emxccompiler | |
| distutils.log | |
| dl | Call C functions in shared objects [Unix]. |
| doctest | Unit testing framework based on running examples embedded in docstrings.
2.5: New SKIP option. New encoding arg to testfile() function. |
| DocXMLRPCServer | Creation of self-documenting XML-RPC servers, using pydoc to create HTML API doc on the fly.
2.5: New attribute rpc_paths. |
| dumbdbm | A dumb and slow but simple dbm clone. |
| |
|
| dummy_thread | |
| dummy_threading | Helpers to make it easier to write code that uses threads where supported, but still runs on Python versions without thread support. The dummy modules simply run the threads sequentially. |
| A package for parsing, handling, and generating email messages. New version 3.0 dropped various deprecated APIs and removes support for Python versions earlier than 2.3. 2.5: Updated to version 4.0. | |
| encodings | New codecs: idna (IDNA strings), koi8_u (Ukranian), palmos (PalmOS 3.5), punycode (Punycode IDNA codec), string_escape (Python string escape codec: replaces non-printable chars w/ Python-style string escapes). New codecs in 2.4: HP Roman8, ISO_8859-11, ISO_8859-16, PCTP-154, TIS-620; Chinese, Japanese and Korean codecs. |
| errno | Standard errno system symbols. The value of each symbol is the corresponding integer value. |
| exceptions | Class based built-in exception hierarchy. |
| fcntl | The fcntl() and ioctl() system calls [Unix]. |
| filecmp | File and directory comparison. |
| fileinput | Helper class to quickly write a loop over all standard input files. 2.5: Made more flexible (Unicode filenames, mode parameter, etc...) |
| |
|
| fnmatch | Filename matching with shell patterns. |
| formatter | Generic output formatting. |
| fpectl | Floating point exception control [Unix]. |
| fpformat | General floating point formatting functions. |
| ftplib | An FTP client class. Based on RFC 959. |
| functools | tools for functional-style programming. See in particular function partial()
[PEP309]. |
| gc | Perform garbage collection, obtain GC debug stats, and tune GC parameters.
2.5: New get_count() function. gc.collect() takes a new
generation argument.
|
| gdbm | GNU's reinterpretation of dbm [Unix]. |
| getopt | Standard command line processing. See also optparse. |
| getpass | Utilities to get a password and/or the current user name. |
| gettext | Internationalization and localization support. |
| glob | Filename "globbing" utility. |
| gopherlib | Gopher protocol client interface. |
| grp | The group database [Unix]. |
| |
|
| gzip | Read & write gzipped files. |
| hashlib | Secure hashes and message digests. |
| heapq | Heap queue (priority queue) helpers.
2.5: nsmallest() and nlargest() takes a
key keyword param. |
| hmac | HMAC (Keyed-Hashing for Message Authentication). |
| hotshot.stones | Helper to run the pystone benchmark under the Hotshot profiler. |
| htmlentitydefs | HTML character entity references. |
| htmllib | HTML2 parsing utilities |
| HTMLParser | Simple HTML and XHTML parser. |
| httplib | HTTP1 client class. |
| idlelib | (package) Support library for the IDLE development environment. |
| ihooks | Hooks into the "import" mechanism. |
| imageop | Manipulate raw image data. |
| imaplib | IMAP4 client.Based on RFC 2060. |
| imghdr | Recognizing image files based on their first few bytes. |
| imp | Access the import internals. |
| imputil | Provides a way of writing customized import hooks. |
| inspect | Get information about live Python objects. |
| itertools | Tools to work with iterators and lazy sequences.
2.5: islice() accepts None for start & step args. |
| keyword | List of Python keywords. |
| linecache | Cache lines from files. |
ossaudiodev(Linux). |
|
| locale | Support for number formatting using the current locale settings.
2.5: format() modified; new fcts format_string() and currency() |
| logging | (package) Tools for structured logging in log4j style. |
| macpath | Pathname (or related) operations for the Macintosh [Mac]. |
| macurl2path | Mac specific module for conversion between pathnames and URLs [Mac]. |
| mailbox | Classes to handle Unix style, MMDF style, and MH style mailboxes. 2.5: added capability to modify mailboxes in addition to reading them. |
| mailcap | Mailcap file handling (RFC 1524). |
| marshal | Internal Python object serialization. |
| markupbase | Shared support for scanning document type declarations in HTML and XHTML. |
| math | Mathematical functions. See also cmath |
| md5 | MD5 message digest algorithm.
2.5: Now a mere wrapper around new library hashlib. |
| mhlib | MH (mailbox) interface. |
| mimetools | Various tools used by MIME-reading or MIME-writing programs. |
| mimetypes | Guess the MIME type of a file. |
| MimeWriter | Generic MIME writer. Deprecated since release 2.3.
Use the email package instead. |
| mimify | Mimification and unmimification of mail messages. |
| mmap | Interface to memory-mapped files - they behave like mutable strings. |
| modulefinder | Tools to find what modules a given Python program uses, without actually running the program. |
| msilib | Read and write Microsoft Installer files [Windows]. |
| msvcrt | File & Console Windows-specific operations [Windows]. |
| multifile | A readline()-style interface to the parts of a multipart message. |
| mutex | Mutual exclusion -- for use with module sched. See also std module threading,
and glock. |
| netrc | Parses and encapsulates the netrc file format. |
| new | Creation of runtime internal objects (interface to interpreter object creation functions). |
| nis | Interface to Sun's NIS (Yellow Pages) [Unix].
2.5: New domain arg to nis.match() and nis.maps(). |
| nntplib | An NNTP client class. Based on RFC 977. |
| ntpath | Common operations on Windows pathnames [Windows]. |
| nturl2path | Convert a NT pathname to a file URL and vice versa [Windows]. |
| olddifflib | Old version of difflib (helpers for computing deltas between objects)? |
| operator | Standard operators as functions.
2.5: itemgetter() and attrgetter() now supports multiple fields. |
| optparse | Improved command-line option parsing library (see also getopt). 2.5: Updated to Optik library 1.51. |
| os | OS routines for Mac, DOS, NT, or Posix depending on what system we're on.
2.5: os.stat() return time values as floats; new constants to os.lseek();
new functions wait3() and wait4(); on FreeBSD, os.stat() returns times
with nanosecond resolution. |
| os.path | Common pathname manipulations. |
| os2emxpath | os.path support for OS/2 EMX. |
| |
|
| parser | Access Python parse trees. |
| pdb | A Python debugger. |
| pickle | Pickling (save/serialize and restore/deserialize) of Python objects (a faster C implementation
exists in built-in module: cPickle).
2.5: Value returned by __reduce__() must be different from None. |
| pickletools | Tools to analyze and disassemble pickles. |
| pipes | Conversion pipeline templates [Unix]. |
| pkgutil | Tools to extend the module search path for a given package. 2.5: PEP302's import hooks support; works for packages in ZIP format archives. |
| platform | Get info about the underlying platform. |
| |
|
| popen2 | Spawn a command with pipes to its stdin, stdout, and optionally stderr. Superseded by module subprocess since 2.4 |
| poplib | A POP3 client class. |
| posix | Most common POSIX system calls [Unix]. |
| posixfile | (deprecated since 1.5, use fcntl.lockf() instead) File-like objects with locking support [Unix]. |
| posixpath | Common operations on POSIX pathnames. |
| pprint | Support to pretty-print lists, tuples, & dictionaries recursively. |
| pre | Support for regular expressions (RE) - see re. |
| profile | Class for profiling python code.
2.5: See also new fast C implementation cProfile |
| pstats | Class for printing reports on profiled python code.
2.5: new stream arg to Stats constructor. |
| pty | Pseudo terminal utilities [Linux, IRIX]. |
| pwd | The password database [Unix]. |
| py_compile | Routine to "compile" a .py file to a .pyc file. |
| pyclbr | Parse a Python file and retrieve classes and methods. |
| pydoc | Generate Python documentation in HTML or text for interactive use. |
| pyexpat | Interface to the Expat XML parser. 2.5: now uses V2.0 of the expat parser. |
| |
unittest. |
| Queue | A multi-producer, multi-consumer queue. |
| quopri | Conversions to/from quoted-printable transport encoding as per RFC 1521. |
| rand | Don't use unless you want compatibility with C's rand(). |
| random | Random variable generators. |
| re | Regular Expressions. |
| readline | GNU readline interface [Unix]. |
| |
|
| |
|
| |
|
| |
|
| repr | Alternate repr() implementation. |
| resource | Resource usage information [Unix]. |
| |
|
| rfc822 | Parse RFC-8222 mail headers. |
| rgbimg | Read and write 'SGI RGB' files. |
| rlcompleter | Word completion for GNU readline 2.0 [Unix].
2.5: Doesn't depend on readline anymore; now works
on non-Unix platforms. |
| robotparser | Parse robot.txt files, useful for web spiders. |
| sched | A generally useful event scheduler class. |
| select | Waiting for I/O completion. |
| sets | A Set datatype implementation based on dictionaries (see Sets). |
| sgmllib | A parser for SGML, using the derived class as a static DTD. |
| sha | SHA-1 message digest algorithm.
2.5: Now a mere wrapper around new library hashlib. |
| shelve | Manage shelves of pickled objects. |
| shlex | Lexical analyzer class for simple shell-like syntaxes. |
| shutil | Utility functions for copying files and directory trees. |
| signal | Set handlers for asynchronous events. |
| SimpleHTTPServer | Simple HTTP Server. |
| SimpleXMLRPCServer | Simple XML-RPC Server.
2.5: New attribute rpc_paths. |
| site | Append module search paths for third-party packages to sys.path. |
| smtpd | An RFC 2821 SMTP server. |
| smtplib | SMTP/ESMTP client class. |
| sndhdr | Several routines that help recognizing sound. |
| socket | Socket operations and some related functions. Now supports timeouts
thru function settimeout(t). Also supports SSL on Windows.
2.5: Now supports AF_NETLINK sockets on Linux; new socket methods
recv_buf(buffer), recvfrom_buf(buffer),
getfamily(), gettype() and getproto() . |
| SocketServer | Generic socket server classes. |
| spwd | Access to the UNIX shadow password database [Unix]. |
| sqlite3 | DB-API 2.0 interface for SQLite databases. |
| sre | Support for regular expressions (RE). See re. |
| stat | Constants/functions for interpreting results of os. |
| statcache | Maintain a cache of stat() information on files. |
| statvfs | Constants for interpreting statvfs struct as returned by os.statvfs()
and os.fstatvfs() (if they exist). |
| string | A collection of string operations (see Strings). |
| StringIO | File-like objects that read/write a string buffer (a faster C implementation exists in built-in module cStringIO). |
| stringprep | Normalization and manipulation of Unicode strings. |
| struct | Perform conversions between Python values and C structs represented as Python strings.
2.5: faster (new pack() and unpack() methods);
pack and unpack to and from buffer objects via methods pack_into and
unpack_from. |
| subprocess | Subprocess management. Replacement for os.system, os.spawn*, os.popen*, popen2.* [PEP324] |
| sunau | Stuff to parse Sun and NeXT audio files. |
| sunaudio | Interpret sun audio headers. |
| symbol | Non-terminal symbols of Python grammar (from "graminit.h"). |
| symtable | Interface to the compiler's internal symbol tables. |
| sys | System-specific parameters and functions. |
| syslog | Unix syslog library routines [Unix]. |
| tabnanny | Check Python source for ambiguous indentation. |
| tarfile | Tools to read and create TAR archives.
2.5: New method TarFile.extractall(). |
| telnetlib | TELNET client class. Based on RFC 854. |
| tempfile | Temporary files and filenames. |
| termios | POSIX style tty control [Unix]. |
| test | Regression tests package for Python. |
| textwrap | Tools to wrap paragraphs of text. |
| thread | Multiple threads of control (see also threading below). |
| threading | New threading module, emulating a subset of Java's threading model.
2.5: New function stack_size([size]) allows to get/set the
stack size for threads created. |
| threading_api | (doc of the threading module). |
| time | Time access and conversions. |
| timeit | Benchmark tool. |
| Tix | Extension widgets for Tk. |
| Tkinter | Python interface to Tcl/Tk. |
| toaiff | Convert "arbitrary" sound files to AIFF (Apple and SGI's audio format). |
| token | Token constants (from "token.h"). |
| tokenize | Tokenizer for Python source. |
| trace | Tools to trace execution of a function or program. |
| traceback | Extract, format and print information about Python stack traces. |
| tty | Terminal utilities [Unix]. |
| turtle | LogoMation-like turtle graphics. |
| types | Define names for all type symbols in the std interpreter. |
| tzparse | Parse a timezone specification. |
| unicodedata | Interface to unicode properties.
2.5: Updated to Unicode DB 4.1.0; Version 3.2.0 still available as
unicodedata.ucd_3_2_0. |
| unittest | Python unit testing framework, based on Erich Gamma's and Kent Beck's JUnit. |
| urllib | Open an arbitrary URL. |
| urllib2 | An extensible library for opening URLs using a variety of protocols. |
| urlparse | Parse (absolute and relative) URLs. |
| user | Hook to allow user-specified customization code to run. |
| |
A wrapper to allow subclassing of built-in dict class
(useless with new-style classes.
Since Python 2.2, dict is subclassable). |
| |
A wrapper to allow subclassing of built-in list class
(useless with new-style classes.
Since Python 2.2, list is subclassable) |
| |
A wrapper to allow subclassing of built-in string class
(useless with new-style classes.
Since Python 2.2, str is subclassable). |
| |
|
| uu | Implementation of the UUencode and UUdecode functions. |
| uuid | UUID objects according to RFC 4122. |
| warnings | Python part of the warnings subsystem. Issue warnings, and filter unwanted warnings. |
| wave | Stuff to parse WAVE files. |
| weakref | Weak reference support for Python. Also allows the creation of proxy objects.
2.5: new methods iterkeyrefs(), keyrefs(),
itervaluerefs() and valuerefs(). |
| webbrowser | Platform independent URL launcher. 2.5: several enhancements (more browsers supported, etc...). |
| |
|
| whichdb | Guess which db package to use to open a db file. |
| whrandom | Wichmann-Hill random number generator (obsolete, use random instead). |
| winsound | Sound-playing interface for Windows [Windows]. |
| wsgiref | WSGI Utilities and Reference Implementation. |
| xdrlib | Implements (a subset of) Sun XDR (eXternal Data Representation). |
| xmllib | A parser for XML, using the derived class as static DTD. |
| xml.dom | Classes for processing XML using the DOM (Document Object Model). 2.3: New modules expatbuilder, minicompat, NodeFilter, xmlbuilder. |
| xml.etree.ElementTree | Subset of Fredrik Lundh's ElementTree library for processing XML. |
| xml.sax | Classes for processing XML using the SAX API. |
| xmlrpclib | An XML-RPC client interface for Python.
2.5: Supports returning datetime objects for the XML-RPC date type. |
| xreadlines | Provides a sequence-like object for reading a file line-by-line without reading the entire file into memory.
Deprecated since release 2.3. Use for line in file instead.
Removed since 2.4 |
| zipfile | Read & write PK zipped files. 2.5: Supports ZIP64 version, a .zip archive can now be larger than 4GB. |
| zipimport | ZIP archive importer. |
| zlib | Compression compatible with gzip.
2.5: Compress and Decompress objects now support
a copy() method. |
| |
|
dir(object) | list valid attributes of object (which can be a module, type or class object) |
dir() | list names in current local symbol table. |
if __name__ == '__main__': | invoke main() if running as script |
map(None, lst1, lst2, ...) | merge lists; see also zip(lst1, lst2, ...) |
b = a[:] | create a copy b of sequence a |
b = list(a) | If a is a list, create a copy of it. |
a,b,c = 1,2,3 | Multiple assignment, same as a=1; b=2; c=3 |
for key, value in dic.items(): ... | Works also in this context |
if 1 < x <= 5: ... | Works as expected |
for line in fileinput.input(): ... | Process each file in command line args, one line at a time |
_ | (underscore) in interactive mode, refers to the last value printed. |
(The following has not been revised, probably not up to date - any contribution welcome -)
Type C-c ? when in python-mode for extensive help.
INDENTATION
Primarily for entering new code:
TAB indent line appropriately
LFD insert newline, then indent
DEL reduce indentation, or delete single character
Primarily for reindenting existing code:
C-c : guess py-indent-offset from file content; change locally
C-u C-c : ditto, but change globally
C-c TAB reindent region to match its context
C-c < shift region left by py-indent-offset
C-c > shift region right by py-indent-offset
MARKING & MANIPULATING REGIONS OF CODE
C-c C-b mark block of lines
M-C-h mark smallest enclosing def
C-u M-C-h mark smallest enclosing class
C-c # comment out region of code
C-u C-c # uncomment region of code
MOVING POINT
C-c C-p move to statement preceding point
C-c C-n move to statement following point
C-c C-u move up to start of current block
M-C-a move to start of def
C-u M-C-a move to start of class
M-C-e move to end of def
C-u M-C-e move to end of class
EXECUTING PYTHON CODE
C-c C-c sends the entire buffer to the Python interpreter
C-c | sends the current region
C-c ! starts a Python interpreter window; this will be used by
subsequent C-c C-c or C-c | commands
VARIABLES
py-indent-offset indentation increment
py-block-comment-prefix comment string used by py-comment-region
py-python-command shell command to invoke Python interpreter
py-scroll-process-buffer t means always scroll Python process buffer
py-temp-directory directory used for temp files (if needed)
py-beep-if-tab-change ring the bell if tab-width is changed