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Python Cheat Sheet by DaveChild

Python cheat sheet

Python sys Variables

argvCommand line args
builti­n_m­odu­le_­namesLinked C modules
byteorderNative byte order
check_­int­ervalSignal check frequency
exec_p­refixRoot directory
executableName of executable
exitfuncExit function name
modulesLoaded modules
pathSearch path
platformCurrent platform
stdin, stdout, stderrFile objects for I/O
versio­n_infoPython version info
winverVersion 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

altsepAltern­ative sep
curdirCurrent dir string
defpathDefault search path
devnullPath of null device
extsepExtension separator
linesepLine separator
nameName of OS
pardirParent dir string
pathsepPatch separator
sepPath 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

%aAbbrev­iated weekday (Sun)
%AWeekday (Sunday)
%bAbbrev­iated month name (Jan)
%BMonth name (January)
%cDate and time
%dDay (leading zeros) (01 to 31)
%H24 hour (leading zeros) (00 to 23)
%I12 hour (leading zeros) (01 to 12)
%jDay of year (001 to 366)
%mMonth (01 to 12)
%MMinute (00 to 59)
%pAM or PM
%SSecond (00 to 61⁴)
%UWeek number¹ (00 to 53)
%wWeekday² (0 to 6)
%WWeek number³ (00 to 53)
%xDate
%XTime
%yYear without century (00 to 99)
%YYear (2008)
%ZTime 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.

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