vectorize and apply on multiply columns in Python

def quality(total_bill, tip):
    if tip/total_bill > 0.25:
        return "Generous"
    else:
        return "Other"

df['Quality'] = df[['total_bill', 'tip']].apply(lambda df: quality(df['total_bill'], df['tip']), axis = 1)

# or
df['Quality'] = np.vectorize(quality)(df['total_bill'], df['tip'])