What is as_index in groupby in pandas?

Question

What exactly is the function of as_index in groupby in Pandas?

Answer 1

When using the group by function, as_index can be set to true or false depending on if you want the column by which you grouped to be the index of the output.

import pandas as pd
table_r = pd.DataFrame({
    'colors': ['orange', 'red', 'orange', 'red'],
    'price': [1000, 2000, 3000, 4000],
    'quantity': [500, 3000, 3000, 4000],
})
new_group = table_r.groupby('colors',as_index=True).count().sort('price', ascending=False)
print new_group

output:

        price  quantity
colors                 
orange      2         2
red         2         2

Now with as_index=False

   colors  price  quantity
0  orange      2         2
1     red      2         2

Note how colors is no longer an index when we change as_index=False