python - 在python中将列表中的数字相乘

Question

我有一个列表:

lst = [[7], [4, 3, 5, 8], [1, 3]]

如何将 list 中的每个元素与其位置相乘:

[[7 * 0],[4 * 0 + 3 * 1 + 5 * 2 + 8 * 3], [1 * 0 + 3 * 1]]

并打印答案:

answer = [[0], [37], [3]]

Answer 1

您可以将列表理解与 sum 和 enumerate 结合使用:

L = [[7], [4, 3, 5, 8], [1, 3]]

res = [[sum(i*j for i, j in enumerate(sublist))] for sublist in L]

print(res)

[[0], [37], [3]]

或者，如果您乐于使用第 3 方库，则可以使用 NumPy:

import numpy as np

L = [[7], [4, 3, 5, 8], [1, 3]]

res = [np.arange(len(sublist)).dot(sublist) for sublist in L]

print(res)

[0, 37, 3]