Question

I have a list of objects representing widgets. Each widget object has a manufactured DateTime field that holds the date and time when the widget was made. All the widgets in the list were manufactured in a particular year.

I would like to get a list with the total widgets manufactured each month – e.g.:

>>> totals
[1, 5, 819, 187, 1, 5, 15, 9, 13, 77, 54, 22]

So in the above list there were 819 widgets made in March.

What’s a pythonic way of doing this?

Answer 1

totals = [0] * 12
for widget in widgets:
    totals[widget.datetime.month - 1] += 1

The indices of totals are in the range 0 to 11, while months usually are in the range 1 to 12, so we need the - 1.

An alternative in Python 2.7 or 3.1 or above:

from collections import Counter
totals = Counter(widget.datetime.month for widget in widgets)