groupby name and position in the group

I ended up using something similar to Stefan’s answer but slightly reformulated it to avoid having to use apply. This looks a bit cleaner to me.

idx1 = df[df['animal'] == 'python'].iloc[:2].index
idx2 = df[df['animal'] == 'python'].iloc[2:].index

df.loc[idx1, "animal"] = "python_1"
df.loc[idx2, "animal"] = "python_2"
df.groupby("animal").sum()