Normalize DataFrame by group

Question

Let\'s say that I have some data generated as follows:

N = 20
m = 3
data = np.random.normal(size=(N,m)) + np.random.normal(size=(N,m))**3

and t

Answer 1

Although this is not the prettiest solution, you could do something like this:

indx = df['indx'].copy()
for indices in df.groupby('indx').groups.values():
    df.loc[indices] -= df.loc[indices].mean()
df['indx'] = indx