StatPlots groupedbar order x axis

JonasIsensee · June 12, 2020, 9:03am

Hi,

so I just figured out how to do it after a lot of digging.

The issue is that in
RecipesPipeline.jl there is
group_labels = sort(collect(unique(v)))

JuliaPlots/RecipesPipeline.jl/blob/304db22c33b64a902dd91606a8886ec371f62809/src/group.jl#L11


      
          # # Grouping
          
          "A special type that will break up incoming data into groups, and allow for easier creation of grouped plots"
          mutable struct GroupBy
              group_labels::Vector                # length == numGroups
              group_indices::Vector{Vector{Int}}  # list of indices for each group
          end
          
          # this is when given a vector-type of values to group by
          function _extract_group_attributes(v::AVec, args...; legend_entry = string)
              group_labels = sort(collect(unique(v)))
              n = length(group_labels)
              if n > 100
                  @warn("You created n=$n groups... Is that intended?")
              end
              group_indices = Vector{Int}[filter(i -> v[i] == glab, eachindex(v)) for glab in group_labels]
              GroupBy(map(legend_entry, group_labels), group_indices)
          end
          
          legend_entry_from_tuple(ns::Tuple) = join(ns, ' ')

Now in theory there are CategoricalArrays for this purpose,
however unique(ctg::CategoricalArray) returns an ordinary Vector{String} instead of a new CategoricalArray.

Defining this solves the problem in this case

function Base.unique(ctg::CategoricalArray)
    l = levels(ctg)
    newctg = CategoricalArray(l)
    levels!(newctg, l)
end

ctg = CategoricalArray(["a", "b", "c", "a", "b", "c"])
levels!(ctg, ["c", "b", "a"])
groupedbar(1:6, group=ctg)

test