pandas：如何通过在 DataFrame 中进行分组来获取行的总和？

Question

I am new to Data Science and I am currently using the Pandas library on the Jupyter notebook. Sorry for my poor English.

A,1,5,9
B,2,6,3
A,3,7,2
B,4,8,1

How to group the above CSV values also adding the contents after creating the DataFrame? I want the output something like this.

    A   B
0   4   6
1   12  14
2   11  4

Thanks in advance:)

Answer 1

You can use df.pivot_table

df
   0  1  2  3
0  A  1  5  9
1  B  2  6  3
2  A  3  7  2
3  B  4  8  1

df.pivot_table(columns=0,aggfunc='sum').rename_axis(columns=None)
    A   B
1   4   6
2  12  14
3  11   4

Answer 2

This is groupby + sum with transpose:

print(df.groupby(0).sum().T.rename_axis(columns=None))

---

    A   B
1   4   6
2  12  14
3  11   4

Note: replace 0 in df.groupby(0) with the actual column name of the first column