How to groupby one value of a column in pandas?-CodePudding

I have two columns that look like this:

Vehicle Brand      Reason of repair

Alfa Romeo         Brakes not working
Honda              Annual Service
BMW                Other
Alfa Romeo         Electrical issues
Honda              Paint
Alfa Romeo         Annual service
Alfa Romeo         Annual service

I want to group by only Alfa Romeo and count the Reasons of repair.

CodePudding user response：

Since you only care about one brand, just filter it with loc and get the value_counts():

df.loc[df['Vehicle Brand'] == 'Alfa Romeo', 'Reason of repair'].value_counts()

# Annual service        2
# Brakes not working    1
# Electrical issues     1
# Name: Reason of repair, dtype: int64

If you really want to groupby, get the groupby.value_counts() of all brands and select Alfa Romeo:

df.groupby('Vehicle Brand')['Reason of repair'].value_counts().loc['Alfa Romeo']

# Reason of repair
# Annual service        2
# Brakes not working    1
# Electrical issues     1
# Name: Reason of repair, dtype: int64