Using group by in DynamoDB

For a project I have to use DynamoDB(aws) and python(with boto).

I have items with a date and I need to display the count grouped by date or by month.

Something like by date of the month [1/2: 5, 2/2: 10, 3/2: 7, 4/2: 30, 5/2: 25, ...] or by month of the year [January: 5, February: 10, March: 7, ...]