"TypeError: 'DataFrame' object is not callable"

Question

I'm trying to compute the mean age of blonde people from the data in df:

np.random.seed(0)
df = pd.DataFrame(
    {
        'Age': [18, 21, 28, 19, 23, 22, 18, 24, 25, 20],
        'Hair colour': [
            'Blonde', 'Brown', 'Black', 'Blonde', 'Blonde',
            'Black','Brown', 'Brown', 'Black', 'Black'],
        'Length (in cm)': np.random.normal(175, 10, 10).round(1),
        'Weight (in kg)': np.random.normal(70, 5, 10).round(1)},
    index=[
        'Leon', 'Mirta', 'Nathan', 'Linda', 'Bandar',
        'Violeta', 'Noah', 'Niji', 'Lucy', 'Mark'],)

I need to get the one number.

Firstly, I attempted to use the "df.divide".

import pandas as pd
import numpy as np

ans_3 = df({'Age'}).divide(df({'Hair colour': ['Blonde']}))

However, I have got this TypeError: 'DataFrame' object is not callable.

What should I do for working my code that I'll get the appropriate result?

Answer 1

Run:

df[df['Hair colour'] == 'Blonde'].Age.mean()

Details:

• df['Hair colour'] == 'Blonde' - generates a Series of bool type, stating whether the current row has Blonde hair.
• df[…] - get rows meeting the above condition.
• Age - from the above rows take only Age column.
• mean() - compute the mean age.