Exercise

# Calculations with .groupby()

The `.groupby()`

method makes life much easier. In this exercise, you'll perform the same calculations as last time, except you'll use the `.groupby()`

method. You'll also perform calculations on data grouped by two variables to see if sales differ by store type depending on if it's a holiday week or not.

`sales`

is available and `pandas`

is loaded as `pd`

.

Instructions 1/2

**undefined XP**

- Group
`sales`

by`"type"`

, take the sum of`"weekly_sales"`

, and store as`sales_by_type`

. - Calculate the proportion of sales at each store type by dividing by the sum of
`sales_by_type`

. Assign to`sales_propn_by_type`

.