Merge pull request #1559 from yha/log-heatmap

Log-scale heatmap edge computation

src/backends/gr.jl

@@ -718,6 +718,12 @@ function gr_display(sp::Subplot{GRBackend}, w, h, viewport_canvas)
         end
         if st == :heatmap
             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)
+                    warn("GR: heatmap only supported with equally spaced data.")
+                end
+            end
             x, y = heatmap_edges(series[:x], sp[:xaxis][:scale]), heatmap_edges(series[:y], sp[:yaxis][:scale])
             xy_lims = x[1], x[end], y[1], y[end]
             expand_extrema!(sp[:xaxis], x)

src/backends/plotly.jl

@@ -587,6 +587,8 @@ function plotly_series(plt::Plot, series::Series)
         return plotly_series_segments(series, d_out, x, y, z)
 
     elseif st == :heatmap
+        x = heatmap_edges(x, sp[:xaxis][:scale])
+        y = heatmap_edges(y, sp[:yaxis][:scale])
         d_out[:type] = "heatmap"
         d_out[:x], d_out[:y], d_out[:z] = x, y, z
         d_out[:colorscale] = plotly_colorscale(series[:fillcolor], series[:fillalpha])

src/utils.jl

@@ -358,19 +358,18 @@ const _scale_base = Dict{Symbol, Real}(
     :ln => e,
 )
 
-"create an (n+1) list of the outsides of heatmap rectangles"
-function heatmap_edges(v::AVec, scale::Symbol = :identity)
+function _heatmap_edges(v::AVec)
   vmin, vmax = ignorenan_extrema(v)
-  extra_min = extra_max = 0.5 * (vmax-vmin) / (length(v)-1)
-  if scale in _logScales
-      vmin > 0 || error("The axis values must be positive for a $scale scale")
-      while vmin - extra_min <= 0
-          extra_min /= _scale_base[scale]
-      end
-  end
+  extra_min = (v[2] - v[1]) / 2
+  extra_max = (v[end] - v[end - 1]) / 2
   vcat(vmin-extra_min, 0.5 * (v[1:end-1] + v[2:end]), vmax+extra_max)
 end
 
+"create an (n+1) list of the outsides of heatmap rectangles"
+function heatmap_edges(v::AVec, scale::Symbol = :identity)
+  f, invf = scalefunc(scale), invscalefunc(scale)
+  map(invf, _heatmap_edges(map(f,v)))
+end
 
 function calc_r_extrema(x, y)
     xmin, xmax = ignorenan_extrema(x)