Python Cheat Sheet: Functions and Tricks, Cheat Sheet of Advanced Computer Programming

Download Python Cheat Sheet: Functions and Tricks and more Cheat Sheet Advanced Computer Programming in PDF only on Docsity! Python Cheat Sheet: Functions and Tricks  Description  Example  Result  A D V A N C E D F U N C T I O N S map(func, iter)  Executes the function on all elements of  the iterable  list(map( ​lambda ​ x: x[ ​0​], [​'red'​, 'green' ​, ​'blue'​])) [​'r'​, ​'g'​, ​'b'​] map(func, i1, ..., ik)  Executes the function on all k elements of  the k iterables  list(map( ​lambda ​ x, y: str(x) + ​' ' ​ + y + ​'s' ​ , [ ​0​, ​2​, ​2​], [​'apple' ​, 'orange'​, ​'banana' ​])) [​'0 apples'​, ​'2 oranges'​, ​'2 bananas'​] string.join(iter)  Concatenates iterable elements  separated by ​string  ' marries '​.join(list([ ​'Alice' ​, 'Bob'​])) 'Alice marries Bob' filter(func, iterable)  Filters out elements in iterable for which  function returns ​False ​ ​(or 0)  list(filter( ​lambda ​ x: ​True ​ ​if​ x> ​17 else ​ ​False ​, [ ​1​, ​15​, ​17​, ​18​])) [​18​] string.strip()  Removes leading and trailing  whitespaces of string  print( ​"\n \t 42 \t "​.strip()) 42 sorted(iter)  Sorts iterable in ascending order  sorted([​8​, ​3​, ​2​, ​42​, ​5​]) [​2​, ​3​, ​5​, ​8​, ​42​] sorted(iter, key=key)  Sorts according to the key function in  ascending order  sorted([​8​, ​3​, ​2​, ​42​, ​5​], key= ​lambda x: ​0​ ​if​ x==​42​ ​else ​ x) [​42​, ​2​, ​3​, ​5​, ​8​] help(func)  Returns documentation of ​func  help(str.upper()) '... to uppercase.' zip(i1, i2, ...)  Groups the i-th elements of iterators ​i1, i2, ... ​ together  list(zip([ ​'Alice' ​, ​'Anna'​], [ ​'Bob'​, 'Jon'​, ​'Frank' ​])) [(​'Alice' ​, ​'Bob' ​), (​'Anna' ​, ​'Jon' ​)] Unzip  Equal to: 1) unpack the zipped list, 2) zip  the result  list(zip(*[( ​'Alice' ​, ​'Bob' ​), (​'Anna' ​, ​'Jon' ​)])) [(​'Alice' ​, ​'Anna'​), (​'Bob' ​, ​'Jon' ​)] enumerate(iter)  Assigns a counter value to each element  of the iterable  list(enumerate([ ​'Alice' ​, ​'Bob' ​, 'Jon'​])) [(​0​, ​'Alice' ​), ( ​1​, 'Bob'​), ( ​2​, ​'Jon'​)] T R I C K S python -m http.server  <P>  Want to share files between PC and phone? Run this command in PC’s shell. <P> is any port number 0–65535. Type <  IP address of PC>:<P> in the phone’s browser. You can now browse the files in the PC directory.  Read comic  import ​ antigravity Open the comic series xkcd in your web browser Zen of Python  import ​ this  '...Beautiful is better than ugly. Explicit is ...' Swapping numbers  Swapping variables is a breeze in Python.  No offense, Java!  a, b = ​'Jane' ​, ​'Alice' a, b = b, a a = ​'Alice' b = ​'Jane' Unpacking arguments  Use a sequence as function arguments  via asterisk operator *. Use a dictionary  (key, value) via double asterisk operator **  def ​ ​f​(x, y, z)​:​ return​ x + y * z f(*[ ​1​, ​3​, ​4​]) f(**{​'z' ​ : ​4​, ​'x' ​ : ​1​, ​'y' ​ : ​3​}) 13 13 Extended Unpacking  Use unpacking for multiple assignment  feature in Python  a, *b = [ ​1​, ​2​, ​3​, ​4​, ​5​] a = ​1 b = [​2​, ​3​, ​4, 5 ​] Merge two dictionaries  Use unpacking to merge two dictionaries  into a single one  x={ ​'Alice' ​ : ​18​} y={ ​'Bob'​ : ​27​, ​'Ann' ​ : ​22​} z = {**x,**y} z = {​'Alice' ​: ​18​, 'Bob'​: ​27​, ​'Ann'​: ​22​}