python enumerate 用法

it2022-05-05  172

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

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

用法:在同时需要index 和 value 值得时候可以使用

line = [1,3,'dfd','jdjfjd'] for i in range(len(line)): item = line[i] print(i,"--->",item) #运行结果: 0 ---> 1 1 ---> 3 2 ---> dfd 3 ---> jdjfjd

等价于下列代码:

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

 

enumerate 实战

line 是个 string 包含 0 和 1,要把1都找出来:

#方法一 def read_line(line): sample = {} n = len(line) for i in range(n): if line[i]!='0': sample[i] = int(line[i]) return sample   #方法二 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'))

转载于:https://www.cnblogs.com/frankb/p/6166304.html

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