python - 如何从列表python中提取索引倍数为2的元素

Question

我只想得到那些索引是二的倍数的那些

    code=[1,2,4,7,2,6,8]
    ncode=[code[i] for i%2==0]

Answer 1

只需使用这种索引方法:

code[::2]

如果你想要奇数索引

code[1::2]

通常，它是这样工作的:

seq = L[start:stop:step]

seq = L[::2] # get every other item, starting with the first
seq = L[1::2] # get every other item, starting with the second