NB: features added in 2.1 since 2.0 are coloured dark green.
NB: features added in 2.0 since 1.5.2 are coloured dark magenta.
Based on:
Python Bestiary, Author: Ken Manheimer, ken.manheimer@nist.gov
Python manuals, Authors: Guido van Rossum and Fred Drake
What's new in Python 2.0, Authors: A.M. Kuchling and Moshe Zadka
python-mode.el, Author: Tim Peters, tim_one@email.msn.com
and the readers of comp.lang.python
Python's nest: http://www.python.org
Development: http://python.sourceforge.net/
ActivePython : http://www.ActiveState.com/ASPN/Python/
newsgroup: comp.lang.python
Help desk: help@python.org
Resources: http://starship.python.net/ and http://www.vex.net/parnassus/
Full documentation: http://www.python.org/doc/
An excellent Python reference book: Python Essential Reference by David Beazley (New Riders)
python [-diOStuUvxX?] [-c command | script | - ] [args] |
Option | Effect |
---|---|
-d | Outputs parser debugging information (also PYTHONDEBUG=x) |
-i | Inspect interactively after running script (also PYTHONINSPECT=x) and force prompts, even if stdin appears not to be a terminal |
-O | Optimize generated bytecode (set __debug__ = 0 =>s suppresses asserts) |
-S | Don't perform 'import site' on initialization |
-t | Issue warnings about inconsistent tab usage (-tt: issue errors) |
-u | Unbuffered binary stdout and stderr (also PYTHONUNBUFFERED=x). |
-U | Force Python to interpret all string literals as Unicode literals. |
-v | Verbose (trace import statements) (also PYTHONVERBOSE=x) |
-x | Skip first line of source, allowing use of non-unix Forms of #!cmd |
-? | Help! |
-c command | Specify the command to execute (see next section). This terminates the option list (following options are passed as arguments to the command). |
script | the name of a python file (.py) to execute read from stdin.
Anything afterward is passed as options to python script or command, not interpreted as an option to interpreter itself. |
args | passed to script or command (in sys.argv[1:]) |
If no script or command, Python enters interactive mode. |
Variable | Effect |
---|---|
PYTHONHOME | Alternate prefix directory (or prefix;exec_prefix). The default module search path uses prefix/lib |
PYTHONPATH | Augments the default search path for module files. The format is the same as the shell's $PATH: one or more directory pathnames separated by ':' or ';' without spaces around (semi-)colons!
On Windows first search for Registry key HKEY_LOCAL_MACHINE\Software\Python\PythonCore\x.y\PythonPath (default value). You may also define a key named after your application with a default string value giving the root directory path of your app. |
PYTHONSTARTUP | If this is the name of a readable file, the Python commands in that file are executed before the first prompt is displayed in interactive mode (no default). |
PYTHONDEBUG | If non-empty, same as -d option |
PYTHONINSPECT | If non-empty, same as -i option |
PYTHONSUPPRESS | If non-empty, same as -s option |
PYTHONUNBUFFERED | If non-empty, same as -u option |
PYTHONVERBOSE | If non-empty, same as -v option |
PYTHONCASEOK | If non-empty, ignore case in file/module names (imports) |
and del for is raise assert elif from lambda return break else global not try class except if or while continue exec import pass def finally in print
Escape | Meaning |
---|---|
\newline | Ignored (escape newline) |
\\ | Backslash (\) |
\e | Escape (ESC) |
\v | Vertical Tab (VT) |
\' | Single quote (') |
\f | Formfeed (FF) |
\OOO | char with octal value OOO |
\" | Double quote (") |
\n | Linefeed (LF) |
\a | Bell (BEL) |
\r | Carriage Return (CR) |
\xHH | char with hex value HH |
\b | Backspace (BS) |
\t | Horizontal Tab (TAB) |
\uHHHH | unicode char with hex value HHHH, can only be used in unicode string |
\UHHHHHHHH | unicode char with hex value HHHHHHHH, can only be used in unicode string |
\AnyOtherChar | left as-is |
- Decimal integer: 1234, 1234567890546378940L (or l)
- Octal integer: 0177, 0177777777777777777L (begin with a 0)
- Hex integer: 0xFF, 0XFFFFffffFFFFFFFFFFL (begin with 0x or 0X)
- Long integer (unlimited precision): 1234567890123456L (ends with L or l)
- Float (double precision): 3.14e-10, .001, 10., 1E3
- Complex: 1J, 2+3J, 4+5j (ends with J or j, + separates (float) real and imaginary parts)
Sequence slicing [starting-at-index : but-less-than-index]. Start defaults to '0'; End defaults to 'sequence-length'.
Dictionary of length 0, 1, 2, etc:
{} {1 : 'first'} {1 : 'first', 'next': 'second'}
Highest | Operator | Comment |
---|---|---|
, [...] {...} `...` | Tuple, list & dict. creation; string conv. | |
s[i] s[i:j] s.attr f(...) | indexing & slicing; attributes, fct calls | |
+x, -x, ~x | Unary operators | |
x**y | Power | |
x*y x/y x%y | mult, division, modulo | |
x+y x-y | addition, substraction | |
x<<y x>>y | Bit shifting | |
x&y | Bitwise and | |
x^y | Bitwise exclusive or | |
x|y | Bitwise or | |
x<y x<=y x>y x>=y x==y x!=y x<>y
x is y x is not y x in s x not in s |
Comparison,
identity, membership |
|
not x | boolean negation | |
x and y | boolean and | |
x or y | boolean or | |
Lowest | lambda args: expr | anonymous function |
Comparison | Meaning | Notes |
---|---|---|
< | strictly less than | (1)
|
<= | less than or equal to | |
> | strictly greater than | |
>= | greater than or equal to | |
== | equal to | |
!= or <> | not equal to | |
is | object identity | (2)
|
is not | negated object identity | (2)
|
Value or Operator | Returns | Notes |
---|---|---|
None, numeric zeros, empty sequences and mappings | False | |
all other values | True | |
not x | True if x is False, else True | |
x or y | if x is False then y, else x | (1)
|
x and y | if x is False then x, else y | (1)
|
None is used as default return value on functions. Built-in single object with type NoneType.
Input that evaluates to None does not print when running Python interactively.
Floats are implemented with C doubles.
Integers are implemented with C longs.
Long integers have unlimited size (only limit is system resources)
Operation | Result |
---|---|
abs(x) | the absolute value of x |
int(x) | x converted to integer |
long(x) | x converted to long integer |
float(x) | x converted to floating point |
-x | x negated |
+x | x unchanged |
x + y | the sum of x and y |
x - y | difference of x and y |
x * y | product of x and y |
x / y | quotient of x and y |
x % y | remainder of x / y |
divmod(x, y) | the tuple (x/y, x%y) |
x ** y | x to the power y (the same as pow(x, y)) |
Operation | >Result |
---|---|
~x | the bits of x inverted |
x ^ y | bitwise exclusive or of x and y |
x & y | bitwise and of x and y |
x | y | bitwise or of x and y |
x << n | x shifted left by n bits |
x >> n | x shifted right by n bits |
Operation | Result | Notes |
---|---|---|
x in s | 1 if an item of s is equal to x, else 0 | |
x not in s | 0 if an item of s is equal to x, else 1 |
|
s + t | the concatenation of s and t | |
s * n, n*s | n copies of s concatenated |
|
s[i] | i'th item of s, origin 0 | (1)
|
s[i:j] | slice of s from i (included) to j (excluded) | (1), (2)
|
len(s) | length of s | |
min(s) | smallest item of s |
|
max(s) | largest item of (s) |
|
Notes :(1) if i or j is negative, the index is relative to the end of the string, ie len(s)+ i or len(s)+j is
Operation | Result | Notes |
---|---|---|
s[i] =x | item i of s is replaced by x | |
s[i:j] = t | slice of s from i to j is replaced by t |
|
del s[i:j] | same as s[i:j] = [] | |
s.append(x) | same as s[len(s) : len(s)] = [x] |
|
s.extend(x) | same as s[len(s):len(s)]= x | (5)
|
s.count(x) | return number of i's for which s[i] == x | |
s.index(x) | return smallest i such that s[i] == x | (1)
|
s.insert(i, x) | same as s[i:i] = [x] if i >= 0 | |
s.remove(x) | same as del s[s.index(x)] | (1)
|
s.pop([i]) | same as x = s[i]; del s[i]; return x | (4)
|
s.reverse() | reverse the items of s in place | (3)
|
s.sort([cmpFct]) | sort the items of s in place | (2), (3)
|
Notes :
(1) raise a ValueError exception when x is not found in s (i.e. out of range).
(2) The sort() method takes an optional argument specifying a comparison fct of 2 arguments (list items) which should
return -1, 0, or 1 depending on whether the 1st argument is considered smaller than, equal to, or larger than the 2nd
argument. Note that this slows the sorting process down considerably.
(3) The sort() and reverse() methods modify the list in place for economy of space when sorting or reversing a large list.
They don't return the sorted or reversed list to remind you of this side effect.
(4) The pop() method is not supported by mutable sequence types other than lists.
The optional argument i defaults to -1, so that by default the last item is removed and returned.
(5) Raises an exception when x is not a list object.
Operation | Result | Notes |
---|---|---|
len(d) | the number of items in d | |
d[k] | the item of d with key k | (1)
|
d[k] = x | set d[k] to x | |
del d[k] | remove d[k] from d | (1)
|
d.clear() | remove all items from d | |
d.copy() | a shallow copy of d | |
d.has_key(k) | 1 if d has key k, else 0 | |
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] = v | (3)
|
d.values() | a copy of d's list of values | (2)
|
d.get(k,defaultval) | the item of d with key k | (4)
|
d.setdefault(k,defaultval) | the item of d with key k | (5)
|
d.popitem() | an arbitrary item of d, and removes item. |
|
Notes :
TypeError is raised if key is not acceptable
(1) KeyError is raised if key k is not in the map
(2) Keys and values are listed in random order
(3) d2 must be of the same type as d1
(4) Never raises an exception if k is not in the map, instead it returns defaultVal. defaultVal is optional, when not provided and k is not in the map, None is returned.
(5) Never raises an exception if k is not in the map, instead it returns defaultVal, and adds k to map with value defaultVal. defaultVal is optional. When not provided and k is not in the map, None is returned and added to map.
Operation | Result | Notes |
---|---|---|
s.capitalize() | return a copy of s with only its first character capitalized. |
|
s.center(width) | return a copy of s centered in a string of length width. | (1)
|
s.count(sub[,start[,end]]) | return the number of occurrences of substring sub in string s. | (2)
|
s.encode([encoding[,errors]]) | return an encoded version of s. Default encoding is the current default string encoding. | (3)
|
s.endswith(suffix[,start[,end]]) | return true if s ends with the specified suffix, otherwise return false. | (2)
|
s.expandtabs([tabsize]) | return a copy of s where all tab characters are expanded using spaces. | (4)
|
s.find(sub[,start[,end]]) | return the lowest index in s where substring sub is found. Return -1 if sub is not found. | (2)
|
s.index(sub[,start[,end]]) | like find(), but raise ValueError when the substring is not found. | (2)
|
s.isalnum() | return true if all characters in s are alphanumeric, false otherwise. | (5)
|
s.isalpha() | return true if all characters in s are alphabetic, false otherwise. | (5)
|
s.isdigit() | return true if all characters in s are digit characters, false otherwise. | (5)
|
s.islower() | return true if all characters in s are lowercase, false otherwise. | (6)
|
s.isspace() | return true if all characters in s are whitespace characters, false otherwise. | (5)
|
s.istitle() | return true if string s is a titlecased string, false otherwise. | (7)
|
s.isupper() | return true if all characters in s are uppercase, false otherwise. | (6)
|
s.join(seq) | return a concatenation of the strings in the sequence seq, seperated by 's's. |
|
s.ljust(width) | return s left justified in a string of length width. | (1), (8)
|
s.lower() | return a copy of s converted to lowercase. |
|
s.lstrip() | return a copy of s with leading whitespace removed. |
|
s.replace(old, new[, maxsplit]) | return a copy of s with all occurrences of substring old replaced by new. | (9)
|
s.rfind(sub[,start[,end]]) | return the highest index in s where substring sub is found. Return -1 if sub is not found. | (2)
|
s.rindex(sub[,start[,end]]) | like rfind(), but raise ValueError when the substring is not found. | (2)
|
s.rjust(width) | return s right justified in a string of length width. | (1), (8)
|
s.rstrip() | return a copy of s with trailing whitespace removed. |
|
s.split([sep[,maxsplit]]) | return a list of the words in s, using sep as the delimiter string. | (10)
|
s.splitlines([keepends]) | return a list of the lines in s, breaking at line boundaries. | (11)
|
s.startswith(prefix[,start[,end]]) | return true if s starts with the specified prefix, otherwise return false. | (2)
|
s.strip() | return a copy of s with leading and trailing whitespace removed. |
|
s.swapcase() | return a copy of s with uppercase characters converted to lowercase and vice versa. |
|
s.title() | return a titlecased copy of s, i.e. words start with uppercase characters, all remaining cased characters are lowercase. |
|
s.translate(table[,deletechars]) | return a copy of s mapped through translation table table. | (12)
|
s.upper() | return a copy of s converted to uppercase. |
|
Notes :
(1) Padding is done using spaces.
(2) If optional argument start is supplied, substring s[start:] is processed. If optional arguments start and end are supplied, substring s[start:end] is processed.
(3) 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'.
(4) If optional argument tabsize is not given, a tab size of 8 characters is assumed.
(5) Returns false if string s does not contain at least one character.
(6) Returns false if string s does not contain at least one cased character.
(7) A titlecased string is a string in which uppercase characters may only follow uncased characters and lowercase characters only cased ones.
(8) s is returned if width is less than len(s).
(9) If the optional argument maxsplit is given, only the first maxsplit occurrences are replaced.
(10) If sep is not specified or None, any whitespace string is a separator. If maxsplit is given, at most maxsplit splits are done.
(11) Line breaks are not included in the resulting list unless keepends is given and true.
(12) table must be a string of length 256. All characters occurring in the optional argument deletechars are removed prior to translation.
formatString % args--> evaluates to a string |
'%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.)
Conversion | Meaning |
---|---|
d | Signed integer decimal. |
i | Signed integer decimal. |
o | Unsigned octal. |
u | Unsigned decimal. |
x | Unsigned hexidecimal (lowercase). |
X | Unsigned hexidecimal (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). |
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.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. |
f.readlines() | Read until EOF with readline() and return 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. |
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.write(str) | Write string to file f. |
f.writelines(list) | Write list of strings to file f. |
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 endunless 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. Defaultsto current namespaces. x can be a string, fileobject or a function object. |
callable(value,... [id=value], [*args], [**kw]) | Call function callable with parameters. Parameters can be passed by name or be omitted if functiondefines default values. E.g. if callable is defined as "def callable(p1=1, p2=2)"
"callable()" <=> "callable(1, 2)" "callable(10)" <=> "callable(10, 2)" "callable(p2=99)" <=> "callable(1, 99)" *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)
|
a += b | Roughly equivalent to a = a + b | (2)
|
a -= b | Roughly equivalent to a = a - b | (2)
|
a *= b | Roughly equivalent to a = a * b | (2)
|
a /= b | Roughly equivalent to a = a / b | (2)
|
a %= b | Roughly equivalent to a = a % b | (2)
|
a **= b | Roughly equivalent to a = a ** b | (2)
|
a &= b | Roughly equivalent to a = a & b | (2)
|
a |= b | Roughly equivalent to a = a | b | (2)
|
a ^= b | Roughly equivalent to a = a ^ b | (2)
|
a >>= b | Roughly equivalent to a = a >> b | (2)
|
a <<= b | Roughly equivalent to a = a << b | (2)
|
Statement | Result |
---|---|
if condition: suite
[elif condition: suite]* [else: suite] |
usual if/else_if/else statement |
while condition: suite
[else: suite] |
usual while statement. "else" suite is executedafter 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."else" suite executed at end unless loop exitedwith "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. |
Statement | Result |
---|---|
assert expr[, message] | expr is evaluated. if false, raises exception AssertionErrorwith message. Inhibited if __debug__ is 0. |
try: suite1
[except [exception [, value]: suite2]+ [else: suite3] |
Statements in suite1 are executed. If an exception occurs, lookin "except" clauses for matching <exception>. If matches or bare"except" execute suite of that clause. If no exception happenssuite in "else" clause is executed after suite1.If exception has a value, it is put in value.exception can also be tuple of exceptions, e.g."except (KeyError, NameError), val: print val" |
try: suite1
finally: suite2 |
Statements in suite1 are executed. If noexception, execute suite2 (even if suite1 isexited with a "return", "break" or "continue"statement). If exception did occur, executessuite2 and then immediately reraises exception. |
raise exception [,value [, traceback]] | Raises exception with optional valuevalue. Arg traceback specifies a traceback object touse when printing the exception's backtrace. |
raise | A raise statement without arguments re-raises the last exception raised in the current function |
my_exception = 'You did something wrong'
try:
if bad:
raise my_exception, bad
except my_exception, value:
print 'Oops', value
class text_exception(Exception): pass try: if bad: raise text_exception() # This is a shorthand for the form # "raise <class>, <instance>" except Exception: print 'Oops' # This will be printed because # text_exception is a subclass of Exception When an error message is printed for an unhandled exception which is a class, the class name is printed, then a colon and a space, and finally the instance converted to a string using the built-in function str().
All built-in exception classes derives from StandardError, itself derived from Exception.
Packages (>1.5): a package is a name space which maps to a directory including module(s) and the special initialization module '__init__.py' (possibly empty). Packages/dirs can be nested. You address a module's symbol via '[package.[package...]module.symbol's.
Statement | Result |
---|---|
import module1 [as name1] [, module2]* | Imports modules. Members of module must bereferred to by qualifying with [package.]module name:"import sys; print sys.argv:""import package1.subpackage.module; package1.subpackage.module.foo()"
module1 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 argv" "from package1 import module; module.foo()" "from package1.module import foo; foo()" name1 renamed as othername1, if supplied. |
from module import * | Imports all names in module, except those starting with "_"
*to be used sparsely, beware of name clashes* "from sys import *; print argv" "from package.module import *; print x' Only 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 definedin the package's __init__.py file, not those in the template 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 "a" is name that hasn't been used in function or module so far: - Try to read from "a" -> NameError - Try to write to "a" -> creates "a" local to function If "a" not defined in fct, but is in module, then: - Try to read from "a", gets value from module - Try to write to "a", creates "a" local to fct But note "a[0]=3" starts with search for "a", will use to global "a" if no local "a". |
def func_id ([param_list]): suite -- Creates a function object & binds it to name func_id.
param_list ::= [id [, id]*] id ::= value | id = value | *id | **id[Args are passed by value.Thus only args representing a mutable object can be modified (are inout parameters). Use a tuple to return more than one value]
Example: def test (p1, p2 = 1+1, *rest, **keywords): -- Parameters with "=" have default value (v is evaluated when function defined). If list has "*id" then id is assigned a tuple of all remaining args passed to function (like C vararg) If list has "**id" then id is assigned a dictionary of all extra arguments passed as keywords.
class <class_id> [(<super_class1> [,<super_class2>]*)]: <suite> -- Creates a class object and assigns it name <class_id> <suite> may contain local "defs" of class methods and assignments to class attributes. Example: class my_class (class1, class_list[3]): ... Creates a class object inheriting from both "class1" and whatever class object "class_list[3]" evaluates to. Assigns new class object to name "my_class". - First arg to class methods is always instance object, called 'self' by convention. - Special method __init__() is called when instance is created. - Special method __del__() called when no more reference to object. - Create instance by "calling" class object, possibly with arg (thus instance=apply(aClassObject, args...) creates an instance!) - In current implementation, can't subclass off built-in classes. But can "wrap" them, see UserDict & UserList modules, and see __getattr__() below. Example: 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" Call parent's super class by accessing parent's method directly and passing "self" explicitly (see "call_parent" in example above). Many other special methods available for implementing arithmetic operators, sequence, mapping indexing, etc.
Example: class C: "A description of C" def __init__(self): "A description of the constructor" # etc. Then c.__doc__ == "A description of C". Then c.__init__.__doc__ == "A description of the constructor".
lambda [param_list]: returnedExpr -- Creates 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 comprehensions
result = [expression for item1 in sequence1 [if condition1] [for item2 in sequence2 ... for itemN in sequenceN] ]is equivalent to:
result = [] for item1 in sequence1: for item2 in sequence2: ... for itemN in sequenceN: if (condition1) and further conditions: result.append(expression)
Function | Result |
---|---|
__import__(name[, globals[, locals[, from list]]]) | Imports module within the given context (see lib ref for more details) |
abs(x) | Return the absolute value of number x. |
apply(f, args[, keywords]) | Calls func/method f with arguments args and optional keywords. |
callable(x) | Returns 1 if x callable, else 0. |
chr(i) | Returns one-character string whose ASCII code isinteger i |
cmp(x,y) | Returns negative, 0, positive if x <, ==, > to y |
coerce(x,y) | Returns a tuple of the two numeric arguments converted to a common type. |
compile(string, filename, kind) | 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 eg. '<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'. |
complex(real[, image]) | Builds a complex object (can also be done using J or j suffix,e.g. 1+3J) |
delattr(obj, name) | deletes attribute named name of object obj <=> del obj.name |
dir([object]) | If no args, returns the list of names in current local symbol table. With a module, class or class instance object as arg, returns list of names in its attr. dict. |
divmod(a,b) | Returns tuple of (a/b, a%b) |
eval(s[, globals[, locals]]) | Eval string s in (optional) globals, locals contexts. s must have no NUL's or newlines. s can also be a code object.Example: x = 1; incr_x = eval('x + 1') |
execfile(file[, globals[, locals]]) | Executes a file without creating a new module, unlike import. |
filter(function, sequence) | Constructs a list from those elements of sequence for whichfunction returns true. function takes one parameter. |
float(x) | Converts a number or a string to floating point. |
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 current global variables. |
hasattr(object, name) | Returns true if object has attr called name. |
hash(object) | Returns the hash value of the object (if it has one) |
hex(x) | Converts a number x to a hexadecimal string. |
id(object) | Returns a unique 'identity' integer for an object. |
input([prompt]) | Prints prompt if given. Reads input and evaluates it. |
int(x[, base]) | Converts a number or a string to a plain integer. Optional base paramenter specifies base from which to convert string values. |
intern(aString) | Enters aString in the table of "interned strings" and returns the string. Interned strings are 'immortals'. |
isinstance(obj, class) | returns true if obj is an instance of class. If issubclass(A,B) then isinstance(x,A) => isinstance(x,B) |
issubclass(class1, class2) | returns true if class1 is derived from class2 |
len(obj) | Returns the length (the number of items) of an object (sequence, dictionary, or instance of class implementing __len__). |
list(sequence) | Converts sequence into a list. If 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 paramenter specifies base from which to convert string values. |
map(function, list, ...) | Applies function to every item of list and returns a list of the results. If additional arguments are passed, function must take that many arguments and it is givent o function on each call. |
max(seq) | Returns the largest item of the non-empty sequence seq. |
min(seq) | Returns the smallest item of a non-empty sequence seq. |
oct(x) | Converts a number to an octal string. |
open(filename [, mode='r', [bufsize=implementation dependent]]) | Returns a new file object. filename is the file name to be opened. mode indicates how the file is to be opened:
'r' for reading 'w' for writing (truncating an existing file) 'a' opens it for appending '+' (appended to any of the previous modes) open the file for updating (note that 'w+' truncates the file) 'b' (appended to any of the previous modes) open the file in binary mode bufsize is 0 for unbuffered, 1 for line-buffered, negative for sys-default, all else, of (about) given size. |
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. |
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 oflist so as to reduce the list to a single value.I f init 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 redefineable (__repr__). See also str() |
round(x, n=0) | Returns the floating point value x rounded to n digits after the decimal point. |
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. |
str(object) | Returns a string containing a nicely printable representation of an object. Class overridable (__str__).See also repr(). |
tuple(sequence) | Creates a tuple with same elements as sequence. If already a tuple, return 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 recommended to use the following form:if isinstance(x, types.StringType): etc... |
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'}. |
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'ss ymbol table. Useful with "%" 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 abig range and little memory. |
zip(seq1[, seq2, ...]) | Returns a list of tuples where each tuple contains the nth element of each of the argument sequences. |
Standard methods & operators map to special '__methods__' and thus may be redefined (mostly in in user-defined classes), e.g.: class x: def __init__(self, v): self.value = v def __add__(self, r): return self.value + r a = x(3) # sort of like calling x.__init__(a, 3) a + 4 # is equivalent to a.__add__(4)
Method | Description |
---|---|
__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... |
__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 |
__nonzero__(self) | Returns 0 or 1 for truth value testing |
__getattr__(self, name) | Called when attr lookup doesn't find <name> |
__setattr__(self, name, value) | Called when setting an attr (inside, don't use "self.name = value", use "self.__dict__[name] = value") |
__delattr__(self, name) | Called to delete attr <name |
__call__(self, *args) | called when an instance is called as function. |
See list in the operator module. Operator function names are provided with 2 variants, with or without leading & trailing '__' (eg. __add__ or add).
Operation | Special method |
---|---|
self+other | __add__(self,other) |
self-other | __sub__(self,other) |
self*other | __mul__(self,other) |
self/other | __div__(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) |
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) |
Method | Descripion |
---|---|
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) |
Operation | Special method | Notes | |
---|---|---|---|
All sequences and maps: | |||
len(s) | __len__(s) | length of object, >= 0. Length 0 == false | |
s[i] | __getitem__(s,i) | Element at index/key i, origin 0 | |
Sequences, general methods, plus: | |||
s[i]=v | __setitem__(s,i,v) | ||
del s[i] | __delitem__(s,i) | ||
s[i:j] | __getslice__(s,i,j) | ||
s[i:j]=seq | __setslice__(s,i,j,seq) | ||
del s[i:j] | __delslice__(s,i,j) | s[i:j] = [] | |
seq * n | __repeat__(seq, n) | ||
s1 + s2 | = __concat__(s1, s2) | ||
i in s | __contains__(s, i) | ||
Mappings, general methods, plus | |||
hash(s) | = __hash__(s) | hash value for dictionary references | |
s[k]=v | = __setitem__(s,k,v) | ||
del s[k] | = __delitem__(s,k) |
Attribute | Meaning |
---|---|
__methods__ | (list, R/O): list of method names of the object |
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) |
__path__ | (string/undefined, R/O): fully qualified package name when applies. |
Attribute | Meaning |
---|---|
__doc__ | (string/None, R/W): doc string (<=> __dict__['__doc__']) |
__name__ | (string, R/W): class name (also in __dict__['__name__']) |
__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): 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 |
__members__ | list of attr names: ['__doc__','__name__','__self__']) |
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_firstlineno | (int, R/O): first line number of the function |
co_flags | (int, R/O): flags for the interpreter bit 2 set if fct uses "*arg" syntaxbit 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 |
stop | (any/None, R/O): upperbound |
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. |
check_interval | How often to check for thread switches or signals (measured in number of virtual machine instructions) |
exitfunc | User can set to a parameterless function. It will get called before interpreter exits. |
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 |
modules | Dictionary of modules that have already been loaded. |
path | Search path for external modules. Can be modified by program. sys.path[0] == dir of script executing |
platform | The current platform, e.g. "sunos5", "win32" |
ps1, ps2 | prompts to use in interactive mode. |
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) |
version | string containing version info about Python interpreter. (and also: copyright, dllhandle, exec_prefix, prefix) |
version_info | tuple containing Python version info - (major, minor, micro, level, serial). |
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 ('.') |
pardir | string used to represent parent directory ('..') |
sep | string used to separate directories ('/' or '\'). Tip: use os.path.join() to build portable paths. |
altsep | Alternate sep if applicable (None otherwise) |
pathsep | character used to separate search path components (as in $PATH), eg. ';' for windows. |
linesep | line separator as used in binary files, ie '\n' on Unix, '\r\n' on Dos/Win, '\r' |
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); if fails. |
renames(old, new) | Recursive directory or file renaming; os.error if fails. |
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 |
getpid() | Returns the current process id |
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 '..' |
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(src, dst) | Renames/moves the file or directory src to dst. [error if target name already exists] |
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). |
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 ofpid, exit_status [Not on Windows] |
waitpid(pid, options) | Waits for process pid to complete. Returns tuple ofpid, exit_status [Not on Windows] |
write(fd, str) | Writes str to file fd. Returns nb of bytes written. |
Function | Result |
---|---|
abspath(p) | Returns absolute path for path p, taking current working dir in account. |
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) |
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%] |
getsize(filename) | return the size in bytes of filename. raise os.error. |
getmtime(filename) | return last modification time of filename (integer nb of seconds since epoch). |
getatime(filename) | return last access time of filename (integer nb of seconds since epoch). |
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 intelligently. |
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 belowdirname, e.g., to avoid visiting certain parts of the tree. |
Function | Result |
---|---|
copy(src, dst) | Copies the contents of file src to file dst, retaining file permissions. |
copytree(src, dst[, symlinks]) | Recursively copies an entire directory tree rooted at srcinto dst (which should not already exist). If symlinks is true, links insrc are kept as such in dst. |
rmtree(path[, ignore_errors[, onerror]]) | Deletes an entire directory tree, ignoring errors if ignore_errors true,or calling onerror(func, path, sys.exc_info()) if supplied with func: faulty function, path: concerned file. |
Variable | Meaning |
---|---|
altzone | signed offset of local DST timezone in sec west of the 0th meridian. |
daylight | nonzero if a DST timezone is specified |
Function | Result |
---|---|
time() | return a float representing UTC time in seconds since the epoch. |
gmtime(secs), localtime(secs) | return a tuple representing time : (year aaaa, month(1-12),day(1-31), hour(0-23), minute(0-59), second(0-59), weekday(0-6, 0 is monday), Julian day(1-366), daylight flag(-1,0 or 1)) |
asctime(timeTuple), | |
strftime(format, timeTuple) | return a formated string representing time. |
mktime(tuple) | inverse of localtime(). Return a float. |
strptime(string[, format]) | parse a formated string representing time, return tuple as in gmtime(). |
sleep(secs) | Suspend execution for <secs> seconds. <secs> can be a float. |
Variable | Meaning |
---|---|
digits | The string '0123456789' |
hexdigits, octdigits | legal hexadecimal & octal digits |
letters, uppercase, lowercase, whitespace | Strings containing the appropriate characters |
index_error | Exception raised by index() if substr not found. |
Function | Result |
---|---|
expandtabs(s, tabSize) | returns a copy of string <s> with tabs expanded. |
find/rfind(s, sub[, start=0[, end=0]) | Return 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) | Return a copy of string <s> left/right justified/centerd in a field of given width, padded with spaces. <s> is never truncated. |
lower/upper(s) | Return a string that is (a copy of) <s> in lowercase/uppercase |
split(s[, sep=whitespace[, maxsplit=0]]) | Return a list containing the words of the string <s>,using the string <sep> as a separator. |
join(words[, sep=' ']) | Concatenate 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 occurences of substring<old> replaced by <new>. Limits to <maxsplit> first substitutions if specified. |
strip(s) | Return a string that is (a copy of) <s> without leading and trailing whitespace. see also lstrip, rstrip. |
Handles Unicode strings. Implemented in new module sre, re now a mere front-end for compatibility.
Patterns are specified as strings. Tip: Use raw strings (e.g. r'\w*') to litteralize 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 occurence 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. |
(?=...) | 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 (?=...) |
(?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. |
(?#...) | A comment; ignored. |
(?letter) | letter is one of 'i','L', 'm', 's', 'x'. Set the corresponding flags (re.I, re.L, re.M, re.S, re.X) for the entire RE. |
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 beg 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 (<=> [^O-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]) |
Compile a RE pattern string into a regular expression object.
Flags (combinable by |):
|
escape(string) | return (a copy of) string with all non-alphanumerics backslashed. |
match(pattern, string[, flags]) | if 0 or more chars at beginning of <string> match the RE pattern string,return a corresponding MatchObject instance, or None if no match. |
search(pattern, string[, flags]) | scan thru <string> for a location matching <pattern>, return a corresponding MatchObject instance, or None if no match. |
split(pattern, string[, maxsplit=0]) | split <string> by occurrences of <pattern>. If capturing () are used in pattern, then occurrences of patterns or subpatterns are also returned. |
findall(pattern, string) | return 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]) | return 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 | Descrition |
---|---|
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, return a corresponding MatchObject instance. Return 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]) | Scan through string looking for a location where this regular expression produces a match, and return a corresponding MatchObject instance. Return 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, return 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 tupleif len(tuple)=1 |
start(group), end(group) | returns indices of start & end of substring matched by group (or None if group exists but doesn'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. |
Variables:
pi eFunctions (see ordinary C man pages for info):
acos(x) asin(x) atan(x) atan2(x, y) ceil(x) cos(x) cosh(x) exp(x) fabs(x) floor(x) fmod(x, y) frexp(x) -- Unlike C: (float, int) = frexp(float) ldexp(x, y) log(x) log10(x) modf(x) -- Unlike C: (float, float) = modf(float) pow(x, y) sin(x) sinh(x) sqrt(x) tan(x) tanh(x)
Functions:
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']
Operation | Result |
---|---|
aifc | Stuff to parse AIFF-C and AIFF files. |
anydbm | Generic interface to all dbm clones. (dbhash, gdbm, dbm,dumbdbm) |
asynchat | Support for 'chat' style protocols |
asyncore | Asynchronous File I/O (in select style) |
atexit | Register functions to be called at exit of Python interpreter. |
audiodev | Audio support for a few platforms. |
base64 | Conversions to/from base64 RFC-MIME transport encoding . |
BaseHTTPServer | Base class forhttp services. |
Bastion | "Bastionification" utility (control access to instance vars) |
bdb | A generic Python debugger base class. |
binhex | Macintosh binhex compression/decompression. |
bisect | List bisection algorithms. |
calendar | Calendar printing functions. |
cgi | Wraps the WWW Forms Common Gateway Interface (CGI). |
CGIHTTPServer | CGI http services. |
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. |
colorsys | Conversion functions between RGB and other color systems. |
commands | Tools for executing UNIX commands . |
compileall | Force "compilation" of all .py files in a directory. |
ConfigParser | Configuration file parser (much like windows .ini files) |
copy | Generic shallow and deep copying operations. |
copy_reg | Helper to provide extensibility for pickle/cPickle. |
dbhash | (g)dbm-compatible interface to bsdhash.hashopen. |
difflib | Tool for comparing sequences, and computing the changes required to convert one into another. |
dircache | Sorted list of files in a dir, using a cache. |
dis | Bytecode disassembler. |
distutils | Package installation system. |
doctest | Unit testing framework based on running examples embedded in docstrings. |
dospath | Common operations on DOS pathnames. |
dumbdbm | A dumb and slow but simple dbm clone. |
exceptions | Class based built-in exception hierarchy. |
filecmp | File comparison. |
fileinput | Helper class to quickly write a loop over all standard input files. |
fnmatch | Filename matching with shell patterns. |
formatter | A test formatter. |
fpformat | General floating point formatting functions. |
ftplib | An FTP client class. Based on RFC 959. |
gc | Perform garbacge collection, obtain GC debug stats, and tune GC parameters. |
getopt | Standard command line processing. See also ftp://www.pauahtun.org/pub/getargspy.zip |
getpass | Utilities to get a password and/or the current user name. |
glob | filename globbing. |
gopherlib | Gopher protocol client interface. |
gzip | Read & write gzipped files. |
htmlentitydefs | Proposed entity definitions for HTML. |
htmllib | HTML parsing utilities. |
httplib | HTTP client class. |
ihooks | Hooks into the "import" mechanism. |
imaplib | IMAP4 client.Based on RFC 2060. |
imghdr | Recognizing image files based on their first few bytes. |
imputil | Privides a way of writing customised import hooks. |
inspect | Get information about live Python objects. |
keyword | List of Python keywords. |
knee | A Python re-implementation of hierarchical module import. |
linecache | Cache lines from files. |
linuxaudiodev | Linux /dev/audio support. |
locale | Support for number formatting using the current locale settings. |
macpath | Pathname (or related) operations for the Macintosh. |
macurl2path | Mac specific module for conversion between pathnames and URLs. |
mailbox | A class to handle a unix-style or mmdf-style mailbox. |
mailcap | Mailcap file handling (RFC 1524). |
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. |
mimify | Mimification and unmimification of mail messages. |
mmap | Interface to memory-mapped files - they behave like mutable strings. |
multifile | Class to make multi-file messages easier to handle. |
mutex | Mutual exclusion -- for use with module sched. |
netrc | parses and encapsulates the netrc file format |
nntplib | An NNTP client class. Based on RFC 977. |
ntpath | Common operations on DOS pathnames. |
nturl2path | Mac specific module for conversion between pathnames and URLs. |
os | Either mac, dos or posix depending system. |
pdb | A Python debugger. |
pickle | Pickling (save and restore) of Python objects (a faster Cimplementation exists in built-in module: cPickle). |
pipes | Conversion pipeline templates. |
popen2 | variations on pipe open. |
poplib | A POP3 client class. Based on the J. Myers POP3 draft. |
posixfile | Extended (posix) file operations. |
posixpath | Common operations on POSIX pathnames. |
pprint | Support to pretty-print lists, tuples, & dictionaries recursively. |
profile | Class for profiling python code. |
pstats | Class for printing reports on profiled python code. |
pty | Pseudo terminal utilities. |
py_compile | Routine to "compile" a .py file to a .pyc file. |
pyclbr | Parse a Python file and retrieve classes and methods. |
pydoc | Interactively convert docstrings to HTML or text. |
pyexpat | Interface to the Expay XML parser. |
PyUnit | Unit test framework inspired by JUnit. |
Queue | A multi-producer, multi-consumer queue. |
quopri | Conversions to/from quoted-printable transport encoding. |
rand | Don't use unless you want compatibility with C's rand(). |
random | Random variable generators (obsolete, use whrandom) |
re | Regular Expressions. |
reconvert | Convert old ("regex") regular expressions to new syntax ("re"). |
regex_syntax | Flags for regex.set_syntax(). |
regexp | Backward compatibility for module "regexp" using "regex". |
regsub | Regular expression subroutines. |
repr | Redo repr() but with limits on most sizes. |
rexec | Restricted execution facilities ("safe" exec, eval, etc). |
rfc822 | RFC-822 message manipulation class. |
rlcompleter | Word completion for GNU readline 2.0. |
robotparser | Parse robot.txt files, useful for web spiders. |
sched | A generally useful event scheduler class. |
sgmllib | A parser for SGML. |
shelve | Manage shelves of pickled objects. |
shlex | Lexical analyzer class for simple shell-like syntaxes. |
shutil | Utility functions usable in a shell-like program. |
SimpleHTTPServer | Simple extension to base http class |
site | Append module search paths for third-party packages to sys.path. |
smtplib | SMTP Client class (RFC 821) |
sndhdr | Several routines that help recognizing sound. |
SocketServer | Generic socket server classes. |
stat | Constants and functions for interpreting stat/lstat struct. |
statcache | Maintain a cache of file stats. |
statvfs | Constants for interpreting statvfs struct as returned by os.statvfs() and os.fstatvfs() (if they exist). |
string | A collection of string operations. |
StringIO | File-like objects that read/write a string buffer (a faster C implementation exists in built-in module: cStringIO). |
sunau | Stuff to parse Sun and NeXT audio files. |
sunaudio | Interpret sun audio headers. |
symbol | Non-terminal symbols of Python grammar (from "graminit.h"). |
tabnanny | Check Python source for ambiguous indentation. |
telnetlib | TELNET client class. Based on RFC 854. |
tempfile | Temporary file name allocation. |
threading | Proposed new higher-level threading interfaces |
threading_api | (doc of the threading module) |
toaiff | Convert "arbitrary" sound files to AIFF files . |
token | Tokens (from "token.h"). |
tokenize | Compiles a regular expression that recognizes Python tokens. |
traceback | Format and print Python stack traces. |
tty | Terminal utilities. |
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. |
urllib | Open an arbitrary URL. |
urlparse | Parse URLs according to latest draft of standard. |
user | Hook to allow user-specified customization code to run. |
UserDict | A wrapper to allow subclassing of built-in dict class. |
UserList | A wrapper to allow subclassing of built-in list class. |
UserString | A wrapper to allow subclassing of built-in string class. |
uu | UUencode/UUdecode. |
warnings | Issue warnings, and filter unwanted warnings. |
wave | Stuff to parse WAVE files. |
weakref | Allows the creation of object references which do not force the object to remain extant. Also allows the creation of proxy objects. |
webbrowser | Platform independent URL launcher. |
whichdb | Guess which db package to use to open a db file. |
whrandom | Wichmann-Hill random number generator. |
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 Document Object Model. |
xml.sax | Classes for processing XML using the SAX API. |
xreadlines | Provides a sequence-like object for reading a file line-by-line without reading the entire file into memory. |
zipfile | Read & write PK zipped files. |
sys Interpreter state vars and functions __built-in__ Access to all built-in python identifiers __main__ Scope of the interpreters main program, script or stdin array Obj efficiently representing arrays of basic values math Math functions of C standard time Time-related functions regex Regular expression matching operations marshal Read and write some python values in binary format struct Convert between python values and C structs
getopt Parse cmd line args in sys.argv. A la UNIX 'getopt'. os A more portable interface to OS dependent functionality re Functions useful for working with regular expressions string Useful string and characters functions and exceptions whrandom Wichmann-Hill pseudo-random number generator thread Low-level primitives for working with process threads threading idem, new recommanded interface.
dbm Interface to Unix ndbm database library grp Interface to Unix group database posix OS functionality standardized by C and POSIX standards posixpath POSIX pathname functions pwd Access to the Unix password database select Access to Unix select multiplex file synchronization socket Access to BSD socket interface
tkinter Main interface to Tk
audioop Useful operations on sound fragments imageop Useful operations on images jpeg Access to jpeg image compressor and decompressor rgbimg Access SGI imglib image files
md5 Interface to RSA's MD5 message digest algorithm mpz Interface to int part of GNU multiple precision library rotor Implementation of a rotor-based encryption algorithm
stdwin Standard Window System interface stdwinevents Stdwin event, command, and selection constants rect Rectangle manipulation operations
al SGI audio facilities AL al constants fl Interface to FORMS library FL fl constants flp Functions for form designer fm Access to font manager library gl Access to graphics library GL Constants for gl DEVICE More constants for gl imgfile Imglib image file interface
sunaudiodev Access to sun audio interface
dir(<module>) list functions, variables in <module> dir(); get object keys, defaults to local name space X.__methods__; list of methods supported by X (if any) X.__members__ List of X's data attributes if __name__ == '__main__': main() invoke main if running as script map(None, lst1, lst2, ...) merge lists b = a[:] create copy of seq structure _ in interactive mode, is last value printed
(Not revised, possibly not up to date)
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
(Not revised, possibly not up to date, see 1.5.2 Library Ref section 9.1; in 1.5.2, you may also use debugger integrated in IDLE)
import pdb (it's a module written in Python) -- defines functions : run(statement[,globals[, locals]]) -- execute statement string under debugger control, with optional global & local environment. runeval(expression[,globals[, locals]]) -- same as run, but evaluate expression and return value. runcall(function[, argument, ...]) -- run function object with given arg(s) pm() -- run postmortem on last exception (like debugging a core file) post_mortem(t) -- run postmortem on traceback object <t> -- defines class Pdb : use Pdb to create reusable debugger objects. Object preserves state (i.e. break points) between calls. runs until a breakpoint hit, exception, or end of program If exception, variable '__exception__' holds (exception,value).
h, help brief reminder of commands b, break [<arg>] if <arg> numeric, break at line <arg> in current file if <arg> is function object, break on entry to function <arg> if no arg, list breakpoints cl, clear [<arg>] if <arg> numeric, clear breakpoint at <arg> in current file if no arg, clear all breakpoints after confirmation w, where print current call stack u, up move up one stack frame (to top-level caller) d, down move down one stack frame s, step advance one line in the program, stepping into calls n, next advance one line, stepping over calls r, return continue execution until current function returns (return value is saved in variable "__return__", which can be printed or manipulated from debugger) c, continue continue until next breakpoint a, args print args to current function rv, retval prints return value from last function that returned p, print <arg> prints value of <arg> in current stack frame l, list [<first> [, <last>]] List source code for the current file. Without arguments, list 11 lines around the current line or continue the previous listing. With one argument, list 11 lines starting at that line. With two arguments, list the given range; if the second argument is less than the first, it is a count. whatis <arg> prints type of <arg> ! executes rest of line as a Python statement in the current stack frame q quit immediately stop execution and leave debugger <return> executes last command again Any input debugger doesn't recognize as a command is assumed to be a Python statement to execute in the current stack frame, the same way the exclamation mark ("!") command does.
(1394) python Python 1.0.3 (Sep 26 1994) Copyright 1991-1994 Stichting Mathematisch Centrum, Amsterdam >>> import rm >>> rm.run() Traceback (innermost last): File "<stdin>", line 1 File "./rm.py", line 7 x = div(3) File "./rm.py", line 2 return a / r ZeroDivisionError: integer division or modulo >>> import pdb >>> pdb.pm() > ./rm.py(2)div: return a / r (Pdb) list 1 def div(a): 2 -> return a / r 3 4 def run(): 5 global r 6 r = 0 7 x = div(3) 8 print x [EOF] (Pdb) print r 0 (Pdb) q >>> pdb.runcall(rm.run) etc.
Always single-steps through top-most stack frame. That is, "c" acts like "n".