Grid plot by factors with Dataframes and Plots

General Usage
2

If your factors go from 1 to M and 1 to N respectively, the simplest would be:

using StatPlots, DataFrames
@df df scatter(:IV, :DV, group = {:Factor1, :Factor2}, layout = (M, N))

For more complex situation I would have thought the following would work and be useful:

plot(layout = (M,N))
by(df, [:Factor1, :Factor2]) do dd
    @df dd scatter!(:IV, :DV, subplot = (:Factor1, :Factor2))
end

But fails for technical reasons. Somehow a SubDataFrame does not have the IterableTables implementation and our plotting macro can’t handle it, I’ll file an issue.