Detailed explanation of the usage of enumerate function in Python

The enumerate function is used to traverse the elements in the sequence and their subscripts. It is mostly used to get the count in the for loop. The enumerate parameter is a traversable variable, such as a string, a list, etc.

Generally When you want to traverse both the index and the elements of a list or array, you will write like this:

for i in range (0,len(list)): 
  print i ,list[i]

However, this method is a bit cumbersome. Using the built-in enumerrate function will be more direct and elegant. Let’s take a look at enumerate first. Definition:

def enumerate(collection): 
  'Generates an indexed series: (0,coll[0]), (1,coll[1]) ...'   
   i = 0 
   it = iter(collection) 
   while 1: 
   yield (i, it.next()) 
   i += 1

enumerate will form an array or list into an index sequence. It is more convenient for us to obtain the index and index content as follows:

for index，text in enumerate(list): 
  print index ,text

Code example 1:

i = 0
seq = ['one', 'two', 'three']
for element in seq:
    print i, seq[i]
    i += 1

0 one

1 two

2 three

Code example 2:

seq = ['one', 'two', 'three']
for i, element in enumerate(seq):
    print i, seq[i]

0 one

1 two

2 three

Code example 3:

for i,j in enumerate('abc'):
    print i,j

0 a

1 b

2 c

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