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

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

Sep 26 '15

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Quick Answer:

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…

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