python - 如何在 python 中合并和求和重复项？

Question

我有一个 numpy 数组:

   [2016-10-20 00:00:00, 6, 17],
   [2016-10-20 00:00:00, 0, 21],
   [2017-09-11 00:00:00, 7, 22],
   [2017-09-11 00:00:00, 5, 30],
   [2017-09-11 00:00:00, 2, 40]

有没有一种简单的方法可以合并具有相同日期的行并对属于同一日期的值求和？

对于上面的例子，它应该是这样的:

   [2016-10-20 00:00:00, 6, 38],
   [2017-09-11 00:00:00, 14, 92]

Answer 1

我建议使用 pandas为此:

import pandas as pd

d = pd.DataFrame([
    ['2016-10-20 00:00:00', 6, 17],
    ['2016-10-20 00:00:00', 0, 21],
    ['2017-09-11 00:00:00', 7, 22],
    ['2017-09-11 00:00:00', 5, 30],
    ['2017-09-11 00:00:00', 2, 40]
])

d.groupby([0]).aggregate(sum)

#                       1   2
# 0
# 2016-10-20 00:00:00   6  38
# 2017-09-11 00:00:00  14  92

请注意 pandas.DataFrame accepts a numpy array as input .