python-cheatsheet/CONDENSED.md

Minimal Python Cheatsheet

Main

if __name__ == '__main__':
    main()

Ranges

range(<from inclusive>, <to exclusive>, <step size>)  # Negative step for backward.
<list>[<from inclusive>:<to exclusive>:<step size>]   # Negative step for backward.
random.randint(<from inclusive>, <to inclusive>)

Dictionary

<dict>.items()
<dict>.get(<key>, <default>)
<dict>.setdefault(<key>, <default>)

Enumerate

for i, <el> in enumerate(<list/dict/set>)

Inline

For

[i+j for i in range(10) for j in range(10) if i+j > 5]

Lambda

lambda <arg1>, <arg2>: <return value>

String

Print

print(<el1>, <el2>, end='', sep='', file=<file>)

Regex

import re
re.sub(<regex>, <new>, <text>)
re.search(<regex>, <text>)

Format

{:<min width>}  -> '<el>    '
{:><min width>} -> '    <el>'
{:^<min width>} -> '  <el>  '
{:_<min width>}  -> '<el>____'
{:.<max width>} -> '<e>'
{:<max widht>.<min width>} -> '    <e>'
{:<max width>.<no of decimals>f} -> '  3.14'

Infinity

float("inf")

Class

Class

class <name>:
    def __init__(self, <arg>):
        self.a = <arg>
    def __repr__(self):
        return str({'a': self.a})
    def __str__(self):
        return str(self.a)

Enum

import enum
class <name>(enum.Enum):
    <value> = <index>

Copy

import copy
copy.copy(<object>)
copy.deepcopy(<object>)

Random

import random
random.random()
random.shuffle(<list>)

Datetime

import datetime
now = datetime.datetime.now()
now.strftime('%Y%m%d')
now.strftime('%Y%m%d%H%M%S')

System

Arguments

import sys
sys.argv

Read

with open(<filename>, encoding='utf-8') as file:
    return file.readlines()

Write

with open(<filename>, 'w', enconding='utf-8') as file:
    file.write(<text>)

Execute Command

import os
os.popen(<command>).read()

JSON

import json

Read

with open(<filename>, encoding='utf-8') as file:
    return json.load(file)

Write

with open(<filename>, 'w', enconding='utf-8') as file:
    file.write(json.dumps(<object>))

SQLite

import sqlite3
db = sqlite3.connect(<filename>)

Read

cursor = db.execute(<query>)
if cursor:
    cursor.<fetchone/fetchall>()
db.close()

Write

db.execute(<query>)
db.commit()