It is sometimes necessary to interpolate colors when you interpolate values that do not contain numbers but rather RGB or HSL color code. This recipe addresses the question how can you define scales for color codes and perform interpolation on them?
Open your local copy of the following file in your web browser:
https://github.com/NickQiZhu/d3-cookbook-v2/blob/master/src/chapter4/color-interpolation.html .
Color interpolation is such a common operation in visualization that D3 actually provides a number of different kinds of interpolators dedicated to color supporting, for example, RGB, HSL, L*a*b*, HCL, and Cubehelix color space. In this recipe, we will demonstrate how color interpolation can be performed in RGB color space. However, all other color interpolators work in the same way.