import numpy as np

import pandas as pd

list('AAAABBBBBBBBCCCCCC'),

df

(x - x.mean())/x.std())

(x - x.mean())/x.std())

df_transformed.set_index(df['c1'], inplace=True)

df_transformed

df_transformed.groupby(level=0).agg(['mean', 'std'])

(x - x.min())/(x.max() - x.min()))

