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Detailed explanation on the usage of enumerate function in Python

高洛峰
高洛峰Original
2017-03-16 16:05:052005browse

enumerateFunction 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 string , list, etc.

Generally, for a list or array when both index and elements need to be traversed , it will be written like this:

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

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

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 group the array or list into an index sequence. This makes it 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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