Pandas sorting multiple columns

Question

I have the following dataframe

How can I sort it as follows:

Column A is sorted based on the sum of corresponding values in column B in descending order(The sums are b-50, a-40, c-15) .

Zero · Accepted Answer · 2017-12-28 09:50:13Z

2

Create a temporary column _t and sort using sort_values on _t, B

In [269]: (df.assign(_t=df['A'].map(df.groupby('A')['B'].sum()))
            .sort_values(by=['_t', 'B'], ascending=False)
            .drop('_t', 1))
Out[269]:
    A   B
6   b  20
10  b  15
0   b  10
1   b   5
2   a  25
7   a  10
3   a   5
4   c   6
8   c   4
9   c   3
5   c   2

Details

In [270]: df.assign(_t=df['A'].map(df.groupby('A')['B'].sum()))
Out[270]:
    A   B  _t
0   b  10  50
1   b   5  50
2   a  25  40
3   a   5  40
4   c   6  15
5   c   2  15
6   b  20  50
7   a  10  40
8   c   4  15
9   c   3  15
10  b  15  50

answered Dec 28, 2017 at 9:50

Zero

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