总和行，列中的值相等 [英] Sum rows where value equal in column

问题描述

如何对numpy数组的第一列中具有相等值的行求和?例如:

How can I sum across rows that have equal values in the first column of a numpy array? For example:

In: np.array([[1,2,3],
             [1,4,6], 
             [2,3,5],
             [2,6,2],
             [3,4,8]])

Out: [[1,6,9], [2,9,7], [3,4,8]]

任何帮助将不胜感激.

推荐答案

Pandas具有非常强大的groupby功能，使此操作非常简单.

Pandas has a very very powerful groupby function which makes this very simple.

import pandas as pd

n = np.array([[1,2,3],
             [1,4,6], 
             [2,3,5],
             [2,6,2],
             [3,4,8]])

df = pd.DataFrame(n, columns = ["First Col", "Second Col", "Third Col"])

df.groupby("First Col").sum()

这篇关于总和行，列中的值相等的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！