Sort a column in Pandas dataframe after groupby operation

Question

I have the following Pandas dataframe:

Fruit   Color   Version
Apple   Green   1.1
Lemon   Green   1.4a
Lemon   Yellow  5
Banana  Black   6.8.a
Banana  Yellow  6.8.a
Lemon   Blue    6.7.a

I would like to group by "Color" column and sort by "Version" column in descending order

The desired output it:

Fruit   Color   Version
Lemon   Green   1.4a
Apple   Green   1.1
Banana  Yellow  6.8.a
Lemon   Yellow  5
Banana  Black   6.8.a
Lemon   Blue    6.7.a

I have tried using LooseVersion library for the version sorting but I can't make it work with 'groupby' method and sort the version inside of each color "chunk"

Answer 1

For the desired output, you don't need to group by but sort for the two columns as follows:

import pandas as pd

df = pd.DataFrame({
    'Fruit': ['Apple', 'Lemon', 'Lemon', 'Banana', 'Banana', 'Lemon'],
    'Color': ['Green', 'Green', 'Yellow', 'Black', 'Yellow', 'Blue'],
    'Version': ['1.1', '1.4a', '5', '6.8.a', '6.8.a', '6.7.a'],
})

print(df)
"""This is your original dataframe
    Fruit   Color Version
0   Apple   Green     1.1
1   Lemon   Green    1.4a
2   Lemon  Yellow       5
3  Banana   Black   6.8.a
4  Banana  Yellow   6.8.a
5   Lemon    Blue   6.7.a
"""

df = df.sort_values(by=['Color', 'Version'], ascending=False)

print(df)
"""This is the sorted dataframe as you want
    Fruit   Color Version
4  Banana  Yellow   6.8.a
2   Lemon  Yellow       5
1   Lemon   Green    1.4a
0   Apple   Green     1.1
5   Lemon    Blue   6.7.a
3  Banana   Black   6.8.a
"""