Introduction to the practical usage of python learning enumerate

A new built-in function, enumerate() , will make certain loops a bit clearer. enumerate(thing) , whereis either an iterator or a sequence, returns an iterator that will return (0,[0]) , (1,[1]) , (2,[2]) , and so forth.

A common idiom to change every element of a list looks like this:

Usage: Can be used when both index and value are needed

line = [1,3,'dfd','jdjfjd']
for i in range(len(line)):
    item = line[i]
    print(i,"--->",item)

#运行结果：
---> 1
---> 3
---> dfd
---> jdjfjd

is equivalent to the following code:

line = [1,3,'dfd','jdjfjd']
for i,item in enumerate(line):
    print(i,"-------",item)

enumerate Actual

line is a string containing 0 and 1, you need to find all 1:

#Method 1

def read_line(line):

sample = {}

n = len(line)

for i in range(n):

if line[i]!='0':

sample[i] = int(line[i])

return sample

#Method 2

def xread_line(line):

return((idx,int(val)) for idx, val in enumerate(line) if val != '0')

print read_line('0001110101')

print list(xread_line('0001110101'))

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