Python pandas dataframe group by based on a condition

Question

My question is simple, I have a dataframe and I groupby the results based on a column and get the size like this:

df.groupby('column').size() 

Now the problem is that I only want the ones where size is greater than X. I am wondering if I can do it using a lambda function or anything similar? I have already tried this:

df.groupby('column').size() > X 

and it prints out some True and False values.

Answer 1

Try this code:

df.groupby('column').filter(lambda group: group.size > X) 

Answer 2

The grouped result is a regular DataFrame, so just filter the results as usual:

 import pandas as pd   df = pd.DataFrame({'a': ['a', 'b', 'a', 'a', 'b', 'c', 'd']})  after = df.groupby('a').size()  >> after  a  a    3  b    2  c    1  d    1  dtype: int64   >> after[after > 2]  a  a    3  dtype: int64