Pandas groupby key then filter based on group and return keys

Question

What is the panda way of doing the following?

data.groupby('id').duration.max().index[data.groupby('id').duration.max() > 365]

I wan't to group by id and then filter using the groups and return the id where the condition was true.

using the group.filter function returns the original dataframe.

Answer 1

You can rewrite your code - it is called boolean indexing with Series from aggregation function max and index :

s = data.groupby('id').duration.max()
idx = s.index[s > 365]
#alternative
#idx = s[s > 365].index

You can also check filtered values of Series :

print(s[s > 365])

But if want filter original DataFrame by max values per groups add GroupBy.transform for return Series with same size as original DataFrame :

data[data.groupby('id').duration.transform('max') > 365]