Answer: Get statistics for each group (such as count, mean, etc) using pandas GroupBy?

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answer re: Get statistics for each group (such as count, mean, etc) using pandas GroupBy?

Sep 26 '15

The simplest way to get row counts per group is by calling .size(), which returns a Series:

df.groupby(['col1','col2']).size()

Usually you want this result as a DataFrame (instead of a Series) so you can do:

df.groupby(['col1', 'col2']).size().reset_index(name='counts')

If you want to find out how to calculate…