py-notes

notes to learn python

String methods:

split()

>>> "hi".split()
["hi"]

Turns the string "hi" in to a list.

isalpha()

If all the characters in a string is alphabetic it returns true, and if it is an alphabetic letter, else it returns false.

>>> "a".isalpha()
True
>>> "0".isalpha()
False

Functions:

list()

creates a list, splits all the letters from a string.

>>> list("hi")
["h","i"]`

Split the string "hi" into a list.

enumerate()

Gives every element in a list an index.

>>> months= ["jan", "feb", "mars"] 
>>> list(enumerate(months)) 
[(0,"jan"), (1,"feb"),(2,"mars")

lambda

With lambda you can create anonymous functions, functions that are not bound to a name.

>>> g = lambda x: x**2
>>> print g(8)
64

max()

Returns the largest item in an iterable or the largest of two or more arguments.

>>> max([1,2,3,4])
4

filter()

Goes through the list, runs the lambda function on every element, and if it returns True, the value stays in the list, other wise, it will get excluded.

>>> words = ["hej", "hello"]
>>> num = 3
>>> list(filter(lambda word: len(word) >num, words))
["hello"]

map()

Goes through the list, runs the lambda function on every element, and return the list.

>>> print(list(map(lambda x: len(x), ["katt"])))
[4]