Python Day2 data types: List tuples and dictionaries

List (List)

A list is a set of ordered sets of data that can be stored in a list in an orderly manner, and can be added to and removed from, and traversed. The list exists in order to store more information through a variable.

through Len () built-in functions to see the number of elements in a list

>>> len (list)

you can find the location of each element in the list by index, remembering that the index is from 0 started with

>>> shopping_list[2] # Find Bike

>>> Shopping_list[0] # The first element is taken out of
>>> Shopping_list[-1] #-1 represents the last element in the list ' Gift '
>>> shopping_list[-3] # take the penultimate 3 -bit element ' Clothes '
>>> shopping_list[-4] # take the bottom 4 elements

slices (Slice)

You can also remove a specified number of elements from the list, which is called slicing

>>> Shopping_list[0:3] #Take0to the first3elements, not including the first4a
>>> Shopping_list[:3] #Ibid., Take0to the first3elements, not including the first4A,0can not write
>>> Shopping_list[2:5] #Take section3to section5an element
>>> Shopping_list[:-3] #take from0to the bottom of the page3an element
>>> shopping_list[-3:] #take the last3an element
>>> Shopping_list[1:8:2] #from1to8take one from the other, the back one.2is the step, that is, every few elements take a
>>> Shopping_list[::2] #take one from each other in place

Change and delete

>>> shopping_list.append (' Movieticket ') #append an element to the back of the list
>>> Shopping_list.pop () #Delete last element
>>> shopping_list.remove (' Mac ') #Delete called' Mac 'the element, if there are multiple' Mac ',that will delete the first one found from the left number
>>> shopping_list[2] = ' COFFEE ' #the index is2the element is changed to"COFFEE", it turns out to be lowercase
>>> Shopping_list.insert (3, "Toy") #inserts a new element, indexed as3

>>> shopping_list.index (' Toy ') #return' Toy 'The index value of the element, if there are multiple identical elements, returns the first matching
>>> shopping_list.append (' food ')
>>> shopping_list.count (' food ') #Statistics' food 'the number of elements, just added one, so now is2a
>>> list2= [' Banana ', ' Apple '] #Create a new list
>>> Shopping_list.extend (list2) #Merge the new list above into theshopping_listin
>>> Shopping_list.sort () #sort the list
>>> Shopping_list.reverse () #Invert the list
>>> del Shopping_list[3:8] #Delete Index3to8the element, not including8
>>> for I in Shopping_list: #Traverse List
... print I

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Python Day2 data types: List tuples and dictionaries