Python Cheat Sheet
WARNING - No descriptions or explainations. If you want to learn and need guidance, CHECK OUR FULL PYTHON TUTORIAL HERE.
Purpose: This is a cheat sheet. It is NOT meant to teach you Python. It is meant as a reference to help you remember syntax. It helps if you find yourself asking things like, “How do you check the length of an array?” or “What is that regex match character?”. We don’t cover everything, just the basics to get things done fast (no classes, eggs, threads, etc.).
Get the PDF right HERE
Get it as an image HERE
Basics
List / Array
| p = [1, q, 4] | create list |
| p[2] = x | assign |
| a.append("new") | append |
| x = a.pop() | pop |
| len(a) | get length |
Comparison Operators
| in, not in, is, is not, and, or, not | Identity |
| == != > < >= <= | Value |
Dictionary / Hash
| d = {'b’ : 1, 'a' : 2 } | dict |
| d['abc'] = 14.50 | assign |
| len(d) | get length |
| del d[key_name] | remove key and value |
| d.remove(value) | first item with value |
| for key in map1: | loop over dict |
Flow Control and Loops
if x < 0: elif x == 0: else: | |
| .... | |
| while b < 10: | while loop |
| while True: | infinite loop |
| for w in words: | "normal" for loop |
| for i in range(len(a)): | array with indices |
| for i in range(5, 10): | 5-9 |
| for k,d in enumerate(a): | dict, loop key/val |
Files
File Management
File IO
File Management
| import os | OS module |
| import shutil | Some utils |
| shutil.copy(src, dst) | Copy file |
| os.rename(src, dst) | rename file |
| os.unlink("/tmp/foo.txt") | delete file |
| os.listdir("/dir") | List files |
| os.mkdir(path[, mode]) | Create directory |
| shutil.copy(src, dst) | copy content and permission |
| os.rmdir(path) | remove dir, only empty dirs |
| os.removedirs(path) | remove empty dir, recursive |
File IO
| f = open('workfile', 'w') | r or w |
| f.write('This is a test\n') | write |
| f.read() | entire file |
| f.readline() | line at a time |
| f.readlines() | entire file, as list |
| f.close() | close it |
Function Syntax
def function1(one, two='Yes', *name2, **name3):
return value
Subprocess / Run OS Commandsimport subprocess subprocess.check_output( "uname -a", stderr=subprocess.STDOUT, shell=True )
Regular Expressions
Basic Usage
Regular Expressions Characters
Flags
Basic Usage
p = re.compile(r”match this”)
m = p.search('string goes here')
if m:
print 'Match found: ', m.group()
else:
print 'No match'
| # r for raw string |
| p.findall() |
# array of tuples # includes groups |
p = re.compile('(a(b)c)d')
m.groups()
| # nested groups |
p = re.compile(r'\W+')
p.split('test test')
| # split, return list |
p = re.compile( '(blue|white|red)') x = p.sub( 'colour', 'blue socks and red shoes') | substitutions |
| p = re.compile('ab*', re.I | re.M) | case insensitive, multi-line |
Regular Expressions Characters
| \d | decimal digit [0-9] |
| \s | whitespace [ \t\n\r\f\v] |
| \w | alphanumeric [a-zA-Z0-9_] |
| ^ | start |
| $ | end |
| . | any character except newline |
| * | 0 or more |
| + | 1 or more |
| ? | 0 or 1 |
| {0,1} | |
Flags
| re.S | Make . match any char, including newlines |
| re.I | Do case-insensitive matches |
| re.M | Multi-line matching, affecting ^ and $ |