python group by 和 count() 多列

问题描述：

我有一个这样的数据框:

I have a data frame like this:

Country  A B C
UK       1 0 1
US       1 1 1
GB       0 1 1
UK       1 1 1
US       0 1 1
GB       0 1 1

我需要按国家/地区分组并计算值为 1 的所有列.我一直坚持为所有列设置条件 == 1.

I need to groupby country and count in all columns where value is 1. I'm stuck on setting the condition of columns == 1 for all them.

结果应该是这样的:

Country  A B C
UK       2 0 2
US       1 2 2
GB       0 2 2

答

因为你在数 1，所以你可以 groupby([]).sum()

Because you are counting 1's you can just groupby([]).sum()

df['country'] = df.index # to generate a new column
result = df.groupby(['country']).sum()

结果如下:

         a  b  c
country         
GB       0  2  2
UK       2  1  2
US       1  2  2