How subtract group columns values in python pandas?

products.groupby(["Product Category"])[["Product Cost","Selling Cost"]].sum()

How to find Selling Margin?

>Solution :

You can use assign to refer to a column in a chain

(products
.groupby(["Product Category"])[["Product Cost","Selling Cost"]]
.sum()
.assign(margin = lambda x: x['Selling Cost'] - x['Product Cost']))