I've heard sum encoding mentioned as a method of encoding categorical variables, but I haven't been able to find a clear explanation of what it actually is.
I found the following explanation on Towards DataScience:
Just like OneHot except one value is held constant and encoded as -1 across all columns.
But this confused me as it doesn't involve any summing.
Is it really just?:
Value Variable 1. Variable 2. Red 1 0 Blue 0 1 Green -1 -1