Overview

A cumulative histogram is a histogram in which each bin stores the count / frequency of itself as well as all the bins with keys ‘smaller’ than the particular bin. As such, a notion of ordering among its keys should be existent in the histogram.

The GIL histogram class has the ability to convert itself into its cumulative version.

Since the container needs to first get an ordering over the keys a key sorting takes place before calculating the cumulative histogram.

Example:

histogram<int, float> h;
/*
Fill histogram ...
*/
auto h1 = cumulative_histogram(h);

Tip: In case you need to store the cumulative histogram elsewhere, consider creating a copy of the histogram and then call the function.