Enumerate () function usage in Python

Enumerate () function usage in Python

First out a topic: 1. There is a list= [1, 2, 3, 4, 5, 6]
Please print the output:
0, 1
1, 2
2, 3
3, 4
4, 5
5, 6
Print output,
2. Reverse list to [6, 5, 4, 3, 2, 1]
3. Select the even number in a and the result is [4, 8, 12]

This example uses the use of enumerate in Python. By the way, enumerate the usage of the count in the For loop, the enumerate argument is a variable that can be traversed, such as a string, a list, etc.; the return value is the enumerate class.

The sample code looks like this:

Problem 1.2.3. Work together, the code is as follows:

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

For I, J in Enumerate (list)

Print (I,J)

LIST2=LIST[::-1]

List3=[i*2 for I in the list if not i%2]//i%2==0 proof i is even, not 0 is true, that is, I is an even number when i*2

Print (LIST2,LIST3)

>>>0,1

>>>1,2

>>>2,3

>>>3,4

>>>4,5

>>>5,6

>>>[6,5,4,3,2,1]

>>>[4,8,12]

You can use enumerate when both the index and value values are required. The following separate strings, arrays, lists, and dictionaries through the elements in the sequence and their subscripts:

One, String:

For i,j in enumerate (' ABCDE '):

Print I,j

>>>0,a

>>>1,b

>>>2,c

>>>3,d

>>>4,e

Two, array:

For i,j in enumerate ((' a ',' B ',' C ')):

　　Print I,j

The output is:

>>>0 A

>>>1,b

>>>2,c

Three, List:

The case has been said at the beginning.

Four, Dictionary:

For I,j in enumerate ({' a ':1,' B ':2}):

　　Print I,j

The output is:

>>>0 A

>>>1,b

Enumerate () function usage in Python