pandas ：给定列的总和DataFrame行 [英] Pandas: sum DataFrame rows for given columns

问题描述

我有以下DataFrame：

I have the following DataFrame:

import pandas as pd
df = pd.DataFrame({'a': [1,2,3], 'b': [2,3,4], 'c':['dd','ee','ff'], 'd':[5,9,1]})

我想添加一列'e'，这是列'a '，'b'和'd'。

I would like to add a column 'e' which is the sum of column 'a', 'b' and 'd'.

跨论坛，我以为这样会有效：

Going across forums, I thought something like this would work:

df['e'] = df[['a','b','d']].map(sum)

但不是！

我想实现具有列列表 ['a'，'b'，'d'] 和 df 作为输入。

I would like to realize the operation having the list of columns ['a','b','d'] and df as inputs.

推荐答案

您可以 sum 并设置参数 axis = 1 总结行，这将忽略无数字列：

You can just sum and set param axis=1 to sum the rows, this will ignore none numeric columns:

In [91]:

df = pd.DataFrame({'a': [1,2,3], 'b': [2,3,4], 'c':['dd','ee','ff'], 'd':[5,9,1]})
df['e'] = df.sum(axis=1)
df
Out[91]:
   a  b   c  d   e
0  1  2  dd  5   8
1  2  3  ee  9  14
2  3  4  ff  1   8

如果您只想对特定列进行总结，那么您可以创建一个列列表，并删除不感兴趣的列：

If you want to just sum specific columns then you can create a list of the columns and remove the ones you are not interested in:

In [98]:

col_list= list(df)
col_list.remove('d')
col_list
Out[98]:
['a', 'b', 'c']
In [99]:

df['e'] = df[col_list].sum(axis=1)
df
Out[99]:
   a  b   c  d  e
0  1  2  dd  5  3
1  2  3  ee  9  5
2  3  4  ff  1  7

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