Modern Python Standard Library Cookbook

Counting frequencies

A very common need in many kinds of programs is to count the occurrences of a value or of an event, which means counting frequency. Be it the need to count words in text, count likes on a blog post, or track scores for players of a video game, in the end counting frequency means counting how many we have of a specific value.

The most obvious solution for such a need would be to keep around counters for the things we need to count. If there are two, three, or four, maybe we can just track them in some dedicated variables, but if there are hundreds, it's certainly not feasible to keep around such a large amount of variables and we will quickly end up with a solution based on a container to collect all those counters.