PyPlot: fix label position and annotate color bar

src/pyplot.jl

@@ -225,24 +225,34 @@ function gridplot!(ctx, TP::Type{PyPlotType}, ::Type{Val{2}}, grid)
     brflag = ones(Bool, nbfaceregions)
     ax.set_aspect(ctx[:aspect])
     tridat = tridata(grid, ctx[:gridscale])
-    cmap = region_cmap(ncellregions)
+    if nbfaceregions ≤ 1
+        # PyPlot.ColorMap cannot handle n ≤ 1, TODO: use other color mapping!
+        cmap = region_cmap( 2 )
+    else
+        cmap = region_cmap(nbfaceregions)
+    end
+
     cdata = ax.tripcolor(tridat...;
                          facecolors = cellcolors(grid, ctx[:cellcoloring]),
                          cmap = PyPlot.ColorMap(cmap, length(cmap)),
-                         vmin = 1.0,
-                         vmax = length(cmap),)
+                         vmin = 0.5,
+                         vmax = length(cmap)+0.5,)
     if ctx[:colorbar] == :horizontal
         cbar = fig.colorbar(cdata;
                             ax = ax,
                             ticks = collect(1:length(cmap)),
-                            orientation = "horizontal",)
+                            orientation = "horizontal",
+                            label = "boundary regions",
+                           )
     end
 
     if ctx[:colorbar] == :vertical
         cbar = fig.colorbar(cdata;
                             ax = ax,
                             ticks = collect(1:length(cmap)),
-                            orientation = "vertical",)
+                            orientation = "vertical",
+                            label = "boundary regions",
+                           )
     end
 
     ax.triplot(tridat...; color = "k", linewidth = ctx[:linewidth])