*65*

You can use the following basic syntax to find the sum of values by group in pandas:

df.groupby(['group1','group2'])['sum_col'].sum().reset_index()

The following examples show how to use this syntax in practice with the following pandas DataFrame:

import pandas as pd #create DataFrame df = pd.DataFrame({'team': ['A', 'A', 'A', 'A', 'B', 'B', 'B', 'B'], 'position': ['G', 'G', 'F', 'C', 'G', 'F', 'F', 'C'], 'points': [25, 17, 14, 9, 12, 9, 6, 4], 'rebounds': [11, 8, 10, 6, 6, 5, 9, 12]}) #view DataFrame df team position points rebounds 0 A G 25 11 1 A G 17 8 2 A F 14 10 3 A C 9 6 4 B G 12 6 5 B F 9 5 6 B F 6 9 7 B C 4 12

**Example 1: Group by One Column, Sum One Column**

The following code shows how to group by one column and sum the values in one column:

#group by team and sum the points df.groupby(['team'])['points'].sum().reset_index() team points 0 A 65 1 B 31

From the output we can see that:

- The players on team A scored a sum of
**65**points. - The players on team B scored a sum of
**31**points.

**Example 2: Group by Multiple Columns, Sum Multiple Columns**

The following code shows how to group by multiple columns and sum multiple columns:

#group by team and position, sum points and rebounds df.groupby(['team', 'position'])['points', 'rebounds'].sum().reset_index() team position points rebounds 0 A C 9 6 1 A F 14 10 2 A G 42 19 3 B C 4 12 4 B F 15 14 5 B G 12 6

From the output we can see that:

- The players on team A in the â€˜Câ€™ position scored a sum of
**9**points and**6**rebounds. - The players on team A in the â€˜Fâ€™ position scored a sum of
**14**points and**10**rebounds. - The players on team A in the â€˜Gâ€™ position scored a sum of
**42**points and**19**rebounds.

And so on.

Note that the **reset_index()** function prevents the grouping columns from becoming part of the index.

For example, hereâ€™s what the output looks like if we donâ€™t use it:

#group by team and position, sum points and rebounds df.groupby(['team', 'position'])['points', 'rebounds'].sum() points rebounds team position A C 9 6 F 14 10 G 42 19 B C 4 12 F 15 14 G 12 6

Depending on how youâ€™d like the results to appear, you may or may not choose to use the **reset_index()** function.

**Additional Resources**

The following tutorials explain how to perform other common grouping operations in pandas:

How to Count Observations by Group in Pandas

How to Find the Max Value by Group in Pandas

How to Calculate Quantiles by Group in Pandas