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'))