are Pandas users masochists or idiots?

bollocks.py

import numpy as np
import pandas as pd

# our goal is to standardize exactly 2 out of 4 columns in a grouped frame,
#   using the within-group standard deviation and mean
df = pd.DataFrame({
    'a': ['Bennie', 'Bennie', 'Bennie', 'The Jets', 'The Jets'],
    'b': [1.0, 3.0, 2.5, 7.1, 8.9],
    'c': [-71.3, -80.4, -68.1, 2.5, 3.4],
    'd': [25, 30, 40, 10, 15] # don't standardize me!
})

df[['b', 'c']] = df.groupby('a')[['b', 'c']].transform(
  lambda x: (x - x.mean()) / x.std())

print(df)