C =cpt4dcw(codes::String, vals::Vector{<:Real}; kwargs...) --> GMTcpt.html)
Create a categorical CPT to use with the output of coast(dcw=...) to make Choropleth maps.
codes is a comma separated string with two chars country codes (ex: “PT,ES,FR,IT”)
vals a vector with same size as country codes, with the values used to colorize the countries.
Optionally provide a CPT in the kwarg cmap=CPT with a range sufficient to transform the vals in colors. As an alternative to the above, provide a makecpt type range numeric vector to create a CPT. If none of these are provided a default CPT = makecpt(range=(0,255,1)) will be used.