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Python 3 Beginner's Reference Cheat Sheet

A Programming › Python cheat sheet in English by paul_benn

Python 3 Beginner's reference

Python Programming Beginner Scripting Python 3 Reference

40,520 views 13,279 downloads 17 Dec 2016 History

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Operators

Assignment	`=`
Arithmetic	`+`, `-`, `*`, `/`, `%`
Comparison	`>`, `>=`, `<`, `<=`, `==`, `!=`
Logical	`not, and, or`

String operations (string s)

`s.count(substring)`	Count occurences
`s.find(substring)`	Index of first occurence
`s.join(sequence)`	Concatenate sequence
`s.split([delimiter])`	Split into list

List operations (list l, element e)

`l.append(e)`	Add e
`l.remove(e)`	Remove e
`l.pop(e)`	Remove and return e
`l.count(e)`	Count occurences
`l.reverse()`	Reverse l
`l.sort()`	Sort l

Dictionary operations (dict d, key k)

`d.clear()`	Clear d
`d.get(k)`	Return d[k]
`d.keys()`	Return keys in d
`d.values()`	Return values in d
`d.items()`	Return key-value pairs in d

File operations (file f)

`f = open(path)`	Open f
`f.read()`	Read f
`f.readline()`	Read line from f
`f.readlines()`	Return list of lines in f
`f.write(s)`	Write s to f
`f.close()`	Close f

In-built functions

`int()`, `float()`, `str()`, `bool()`...	Type casting
`len(data)`	Length
`min(values)`, `max(values)`	Minimum / Maximum
`pow(x,y, [z])`	X to the power Y [mod Z]
`range(start, stop, [step])`	Ordered list
`input()`, `print()`	Console Input/Output
`filter(function, array)`	Filter array
`map(function, array)`	Map function onto array
`id(object)`	Unique object ID
`round(n, [x])`	Round n [x decimal places]

Module import

import module

from module import submodule

Control Flow

`if(cond): <code> else: <code>`	If-else
`if(cond1): <code> elif(cond1): <code> else: <code>`	If-elif-else
`for i in range([start], stop, [step]): <code>`	For loop over range
`for i in items: <code>`	For loop over iterable
`while(condition): <code>`	While loop
`break`	Exit first enclosing loop
`continue`	Skip to next iteration

Useful standard library modules

`math`, `numpy`, `scipy`	Math
`matplotlib`	Graph plotting
`random`	Random generators
`datetime`	Date and time
`timeit`	Performance
`re`	Regular expressions
`os`	OS interaction
`sys`	stdin, stdout, stderr, version
`urllib`	Internet access
`zlib`	Data compression

Object-oriented

`class Person:`	Class definition
`x = Person(age, height)`	Object creation
`x.age`	Field access
`x.birthday()`	Method access

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Comments (1)

dai_xiong 17:07 16 Apr 2018

good

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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.