List of Python basics

List lists

Create list () lists using [] (brackets)

List lists, which can be stored in different types and elements, and can be modified after a defined list.

a=[1,2,3,4,5,6]

B=list ((3,2,3,2))

Alist=list (3,2,3,2,'I am this list')) Blist=['a','b','C','D','e','I'm a list, too .']Print(alist)Print(blist)#Output Result:[3, 2, 3, 2,'I am this list']['a','b','C','D','e','I'm a list, too .']

A, list index---slice [:], [::]

Print (Alist[1:3]) # left-to-right without stop bit 3, supports negative indexes (as in strings) # Output Result: [2, 3]

Print (Blist[1:8:2]) # from right 1 to left 8, the third parameter is Step 2 (one for each) # Output Result: ['b'd' I'm also a list ' ]

 print  (blist[:: -1]) #   reverse direction (reverse list contents)  #   output result:  [ "  I'm also a list  "  ,  e  "  ,  d  "  ,  c  "  ,  b  "  ,  a  "  ]

Print (Blist[4:2:-1]) # -1 Reverse direction take, from right to left, start to index 4 (right to left), end to index 2 (right to left), not end 2 # Output Result: ['e'd']

B, List add element

1, append () (Append to end)

Alist.append (' I'm append add in ')print(alist)#  Output:' I am this list '' I am append add in ']

2, insert () specify position append

Alist.insert (2,' add ' in 2 position ')print(alist)# output Result:  ' add ' in 2 position  ' I am this list '  I'm append added to the ']

3. Modify the list element

alist[2]='2 position modified 'print' (alist)# output:' 2 Location Modified ' ' I am this list ' ' I'm append add it in. ']

4. Popup element--return value

4.1, pop () does not pass the parameter default pop-up last a no-vegetarian

# A pop in the list has a return value, and you can define a variable to receive Print (APOP) #apop接收到弹出来的值, this is the output popup element. Print (alist) # This is the output of the alist # Output Result: I am append added ['2 position modified ' I am this list ']

4.2, Pop () incoming parameters can be specified to eject the non-vegetarian

Bpop=alist.pop (2)# pass in a parameter (list index), you can specify the location of the popup, through the variable Bpop receive the popup value print(bpop)#  Output the received value print(alist)# alist output # output:2 position modified [  ' I am this list ']

C, List nesting

Alist=list ((3,2,3,2, ' I am this list '), blist=[' A ', ' B ', ' C ', ' d ', ' e ', ' I'm a list ')

Alist.append (blist)#Add the blist to the Alist by append () so that a list is nested in a listPrint(alist)#Output Result:[3, 2, 3, 2,'I am this list', ['a','b','C','D','e','I'm a list, too .']]

Nested list values

Print # takes the value of index 3 in the list nested list, and the nested list index position is 5 # output Result:D

D, List length calculation len () alist=[3, 2, 3, 2, ' I am this list ', [' A ', ' B ', ' C ', ' d ', ' e ', ' I am also a list ']

Print (Len (alist)) # Output List Length # Output results:6

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List of Python basics