The PR JuliaData/CategoricalArrays.jl#310 means that an array with elements of type Symbol can no longer be wrapped as a CategoricalArray.

This means all MLJ documentation and test code that uses symbols in categorical data must be refactored to use strings instead.

These repos, at least, need checking/refactoring, in order of priority:

• MLJ

• [x]

From https://forum.astronomie.de/threads/neuer-stacker-kombinierer.290375/post-1480549

Described e.g. here: http://www.robgendlerastropics.com/LLRGB.html