Code Quiz

Vectorized Conditions Gone Wrong

A vectorized Pandas discount calculation fails because of a Python-vs-NumPy logical operator mistake.

Codepython

import numpy as np
import pandas as pd

df = pd.DataFrame({'price': [100, 200, 300], 'qty': [1, 5, 2]})

# Goal: 10% discount when price > 150 AND qty >= 2, else 0%
df['discount'] = np.where(
    (df['price'] > 150) and (df['qty'] >= 2),
    0.10,
    0.00,
)

print(df)

This code raises 'ValueError: The truth value of a Series is ambiguous'. What is the bug and how do you fix it?

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