how to limit the duplicate to 5 in pandas data frames?

Question

col1= ['A','B','A','C','A','B','A','C','A','C','A','A','A']
col2= [1,1,4,2,4,5,6,3,1,5,2,1,1]

df = pd.DataFrame({'col1':col1, 'col2':col2})

for A we have [1,4,4,6,1,2,1,1], 8 items but i want to limit the size to 5 while converting Data frame to dict/list

Output:

Dict = {'A':[1,4,4,6,1],'B':[1,5],'C':[2,3,5]}

Answer 1

Use pandas.DataFrame.groupby with apply:

df.groupby('col1')['col2'].apply(lambda x:list(x.head(5))).to_dict()

Output:

{'A': [1, 4, 4, 6, 1], 'B': [1, 5], 'C': [2, 3, 5]}