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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.argv­gv[0]­gv[1] bar­gv[2] -c­gv[3] qux­gv[4] --h

sys.argv for the command:
$ python 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)
__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)

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)

Python Time Methods

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

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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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 (, 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'.

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