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Python Cheat Sheet by DaveChild

Python cheat sheet

Python sys Variables

argv
Command line args
builti­n_m­odu­le_­names
Linked C modules
byteorder
Native byte order
check_­int­erval
Signal check frequency
exec_p­refix
Root directory
executable
Name of executable
exitfunc
Exit function name
modules
Loaded modules
path
Search path
platform
Current platform
stdin, stdout, stderr
File objects for I/O
versio­n_info
Python version info
winver
Version number

Python sys.argv

sys.ar­gv[0]
foo.py
sys.ar­gv[1]
bar
sys.ar­gv[2]
-c
sys.ar­gv[3]
qux
sys.ar­gv[4]
--h
sys.argv for the command:
$ python foo.py bar -c qux --h

Python os Variables

altsep
Altern­ative sep
curdir
Current dir string
defpath
Default search path
devnull
Path of null device
extsep
Extension separator
linesep
Line separator
name
Name of OS
pardir
Parent dir string
pathsep
Patch separator
sep
Path separator
Registered OS names: "­pos­ix", "­nt",
"­mac­", "­os2­", "­ce", "­jav­a", "­ris­cos­"

Python Class Special Methods

__new_­_(cls)
__lt__­(self, other)
__init­__(­self, args)
__le__­(self, other)
__del_­_(self)
__gt__­(self, other)
__repr­__(­self)
__ge__­(self, other)
__str_­_(self)
__eq__­(self, other)
__cmp_­_(self, other)
__ne__­(self, other)
__inde­x__­(self)
__nonz­ero­__(­self)
__hash­__(­self)
__geta­ttr­__(­self, name)
__geta­ttr­ibu­te_­_(self, name)
__seta­ttr­__(­self, name, attr)
__dela­ttr­__(­self, name)
__call­__(­self, args, kwargs)
 

Python List Methods

append­(item)
pop(po­sition)
count(­item)
remove­(item)
extend­(list)
reverse()
index(­item)
sort()
insert­(po­sition, item)

Python String Methods

capita­lize() *
lstrip()
center­(width)
partit­ion­(sep)
count(sub, start, end)
replac­e(old, new)
decode()
rfind(sub, start ,end)
encode()
rindex­(sub, start, end)
endswi­th(sub)
rjust(­width)
expand­tabs()
rparti­tio­n(sep)
find(sub, start, end)
rsplit­(sep)
index(sub, start, end)
rstrip()
isalnum() *
split(sep)
isalpha() *
splitl­ines()
isdigit() *
starts­wit­h(sub)
islower() *
strip()
isspace() *
swapcase() *
istitle() *
title() *
isupper() *
transl­ate­(table)
join()
upper() *
ljust(­width)
zfill(­width)
lower() *
Methods marked * are locale dependant for 8-bit strings.

Python File Methods

close()
readli­nes­(size)
flush()
seek(o­ffset)
fileno()
tell()
isatty()
trunca­te(­size)
next()
write(­string)
read(size)
writel­ine­s(list)
readli­ne(­size)

Python Indexes and Slices

len(a)
6
a[0]
0
a[5]
5
a[-1]
5
a[-2]
4
a[1:]
[1,2,3­,4,5]
a[:5]
[0,1,2­,3,4]
a[:-2]
[0,1,2,3]
a[1:3]
[1,2]
a[1:-1]
[1,2,3,4]
b=a[:]
Shallow copy of a
Indexes and Slices of a=[0,1­,2,­3,4,5]
 

Python Datetime Methods

today()
fromor­din­al(­ord­inal)
now(ti­mez­one­info)
combin­e(date, time)
utcnow()
strpti­me(­date, format)
fromti­mes­tam­p(t­ime­stamp)
utcfro­mti­mes­tam­p(t­ime­stamp)

Python Time Methods

replace()
utcoff­set()
isofor­mat()
dst()
__str__()
tzname()
strfti­me(­format)

Python Date Formatting

%a
Abbrev­iated weekday (Sun)
%A
Weekday (Sunday)
%b
Abbrev­iated month name (Jan)
%B
Month name (January)
%c
Date and time
%d
Day (leading zeros) (01 to 31)
%H
24 hour (leading zeros) (00 to 23)
%I
12 hour (leading zeros) (01 to 12)
%j
Day of year (001 to 366)
%m
Month (01 to 12)
%M
Minute (00 to 59)
%p
AM or PM
%S
Second (00 to 61⁴)
%U
Week number¹ (00 to 53)
%w
Weekday² (0 to 6)
%W
Week number³ (00 to 53)
%x
Date
%X
Time
%y
Year without century (00 to 99)
%Y
Year (2008)
%Z
Time zone (GMT)
%%
A literal "­%" character (%)
¹ Sunday as start of week. All days in a new year preceding the first Sunday are considered to be in week 0.
² 0 is Sunday, 6 is Saturday.
³ Monday as start of week. All days in a new year preceding the first Monday are considered to be in week 0.
⁴ This is not a mistake. Range takes account of leap and double­-leap seconds.
 

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Comments

Brent Hoover Brent Hoover, 07:45 6 Dec 11

This is a great cheatsheet. I'd add a few things, though I don't know what I would remove. I'd add dictionary methods, built-in functions (http://docs.python.org/library/functions.html), and the regular expression functions, since they are odd and I can never remember which one returns what.

Mike Mike, 08:01 17 Sep 12

Hi Dave, thanks for the opensource information. From a Newbie Pythionista wannabe

Desiree Desiree, 21:43 11 Oct 12

Thank you, Dave, for your generosity. This will be helpful in a course I'm taking on 'Programming Fundamentals with Python'.

Samantha Atkins Samantha Atkins, 10:12 30 May 14

I would add:
with patterns and how to roll your own;
list comprehensions;
generators and methods of making them;
decorators;
getattr, hasattr, setattr.

At least I ask people that say they really know python well about these things.

Stan Stan, 17:53 7 Nov 14

Missing, reverse a string
>>> 'hello world'[::-1]
'dlrow olleh'

Brian Brian, 17:53 7 Nov 14

Not "patch"


os.pathsep
The character conventionally used by the operating system to separate search path components (as in PATH), such as colon for POSIX or semicolon for Windows. Also available via os.path.

cosmin cosmin, 20:29 7 Nov 14

Curious, is there a way to download this as a PDF? I'm sometimes away but I like to carry stuff like this with me. Thank you.

johnbuk johnbuk, 16:14 10 Nov 14

Cosmin - click the "Download" link at the top-right of the sheet.

My thanks also to Dave Child for this tool - your work is much appreciated.

Glenn Glenn, 16:22 10 Nov 14

@cosmin - if you click on the thumbnail image to the right of the comments it will pop up a window where you can download the PDF.

codeman38 codeman38, 08:33 24 Nov 14

There seems to be some UTF-8 weirdness with the footnote superscripts in the date formatting section.

DaveChild DaveChild, 08:34 24 Nov 14

Thanks codeman, I've fixed it.

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