alow heatmap of nx1 or 1xn matrices

src/backends/gr.jl

@@ -614,7 +614,7 @@ function _update_min_padding!(sp::Subplot{GRBackend})
             rightpad += 4mm
         else
             leftpad += 4mm
-        end 
+        end
     end
     if sp[:colorbar_title] != ""
         rightpad += 4mm
@@ -671,7 +671,7 @@ function gr_display(sp::Subplot{GRBackend}, w, h, viewport_canvas)
             outside_ticks = true
             for ax in (sp[:xaxis], sp[:yaxis])
                 v = series[ax[:letter]]
-                if diff(collect(extrema(diff(v))))[1] > 1e-6*std(v)
+                if length(v) > 1 && diff(collect(extrema(diff(v))))[1] > 1e-6*std(v)
                     @warn("GR: heatmap only supported with equally spaced data.")
                 end
             end

src/utils.jl

@@ -357,6 +357,7 @@ const _scale_base = Dict{Symbol, Real}(
 )
 
 function _heatmap_edges(v::AVec)
+  length(v) == 1 && return v[1] .+ [-0.5, 0.5]
   vmin, vmax = ignorenan_extrema(v)
   extra_min = (v[2] - v[1]) / 2
   extra_max = (v[end] - v[end - 1]) / 2