python - Pandas Calculate percentage by column values

Question

The dataframe is like below

id	age
a	30-40
b	30-40
c	30-40
d	40-50
e	40-50

question from:https://stackoverflow.com/questions/65896513/pandas-calculate-percentage-by-column-values

Answer 1

Use Series.value_counts with normalize=True, then multiple by 100 and change format to DataFrame:

df1 = (df['age'].value_counts(normalize=True)
                .mul(100)
                .rename_axis('age')
                .reset_index(name='percentage'))
print (df1)
     age  percentage
0  30-40        60.0
1  40-50        40.0