RGB range for cold and warm colors?

Question

What are ranges of cold and warm colors (http://www.diy-bathroom-remodel.com/images/color_wheel.gif) in RGB?

Answer 1

Simple and accurate:

    def is_hot(a):
        return (a[..., 'RED'] > 128)

where 'RED' stands for the index of the red channel in the array a.

This works -- you can see for yourself by: (a) looking at the second wheel by Fabian Fagerholm and/or (b) go to the following link and move the bar up and down towards the two warm ends.

https://www.colorspire.com/rgb-color-wheel/