numpy数组中的多个累积和 [英] Multiple cumulative sum within a numpy array

问题描述

我是numpy的新手，如果对此问题已经提出，我感到抱歉.我正在寻找一种向量化解决方案，该解决方案可以在一维numpy数组中运行多个不同大小的累积.

I'm sort of newbie in numpy so I'm sorry if this question was already asked. I'm looking for a vectorization solution which enable to run multiple cumsum of different size within a one dimension numpy array.

my_vector=np.array([1,2,3,4,5])
size_of_groups=np.array([3,2])

我想要类似的东西

np.cumsum.group(my_vector,size_of_groups)
[1,3,6,4,9]

我不想要带有循环的解决方案. numpy函数或numpy操作.

I do not want a solution with loops. Either numpy functions or numpy operations.

推荐答案

不确定numpy，但是熊猫可以使用groupby + cumsum轻松地做到这一点:

Not sure about numpy, but pandas can do this pretty easily with a groupby + cumsum:

import pandas as pd

s = pd.Series(my_vector)
s.groupby(s.index.isin(size_of_groups.cumsum()).cumsum()).cumsum()

0    1
1    3
2    6
3    4
4    9
dtype: int64

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