python 3.x - Sorting the grouped data as per group size in Pandas -

i have 2 columns in dataset, col1 , col2. want group data per col1 , sort data per size of each group. is, want display groups in ascending order of size.

i have written code grouping , displaying data follows:

grouped_data = df.groupby('col1') """code sorting comes here""" name,group in grouped_data: print (name) print (group)

before displaying data, need sort per group size, not able do.

you can use python's sorted:

in [11]: df = pd.dataframe([[1, 2], [1, 4], [5, 6]], index=['a', 'b', 'c'], columns=['a', 'b'])  in [12]: g = df.groupby('a')  in [13]: sorted(g,  # iterates pairs of (key, corresponding subdataframe)                 key=lambda x: len(x[1]),  # sort number of rows (len of subdataframe)                 reverse=true)  # reverse sort i.e. largest first out[13]:  [(1,     b       1  2      b  1  4),  (5,     b      c  5  6)] 

note: iterator g, iterates on pairs of key , corresponding subframe:

in [14]: list(g)  # happens same above... out[14]: [(1,     b       1  2      b  1  4,  (5,     b      c  5  6)]