Add :symlog axis scaling option (#113)

Author: pjaap

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [1.17.0] - 2026-01-09
+- Add `:symlog` axis scaling for symmetric logarithmic axis scaling, see, e.g. [matplotlib symlog](https://matplotlib.org/stable/gallery/scales/symlog_demo.html)
+- Add `:symlog_threshold` (default = 10.0) to determine when to switch from linear to log scaling in case of `:symlog` scaling
+
 ## [1.16.3] - 2026-01-07
 - Add `title`, `xlabel`, and `ylabel` to 1D and 2D `gridplot!` with `GLMakie`
 - Add `title`, `xlabel`, and `ylabel` to 1D and 2D `gridplot!` with `Py[thon]Plot`

Project.toml

@@ -1,7 +1,7 @@
 name = "GridVisualize"
 uuid = "5eed8a63-0fb0-45eb-886d-8d5a387d12b8"
 authors = ["Juergen Fuhrmann <juergen.fuhrmann@wias-berlin.de>", "Patrick Jaap <patrick.jaap@wias-berlin.de>"]
-version = "1.16.3"
+version = "1.17.0"
 
 [deps]
 ColorSchemes = "35d6a980-a343-548e-a6ea-1d62b119f2f4"

ext/GridVisualizeMakieExt.jl

@@ -474,12 +474,28 @@ function scalarplot!(ctx, TP::Type{MakieType}, ::Type{Val{1}}, grids, parentgrid
     if !haskey(ctx, :scene)
         ctx[:xtitle] = Observable(ctx[:title])
 
+        if ctx[:xscale] == :log
+            xscale = log10
+        elseif ctx[:xscale] == :symlog
+            xscale = XMakie.Makie.Makie.Symlog10(ctx[:symlog_threshold])
+        else
+            xscale = identity
+        end
+
+        if ctx[:yscale] == :log
+            yscale = log10
+        elseif ctx[:yscale] == :symlog
+            yscale = XMakie.Makie.Makie.Symlog10(ctx[:symlog_threshold])
+        else
+            yscale = identity
+        end
+
         # Axis
         ctx[:scene] = XMakie.Axis(
             ctx[:figure];
             title = map(a -> a, ctx[:xtitle]),
-            xscale = ctx[:xscale] == :log ? log10 : identity,
-            yscale = ctx[:yscale] == :log ? log10 : identity,
+            xscale,
+            yscale,
             xlabel = ctx[:xlabel],
             ylabel = ctx[:ylabel],
             scenekwargs(ctx)...,

ext/GridVisualizePlotsExt.jl

@@ -260,6 +260,13 @@ function scalarplot!(ctx, TP::Type{PlotsType}, ::Type{Val{1}}, grids, parentgrid
         ymax = ylimits[2]
     end
 
+    for key in (:xscale, :yscale)
+        if ctx[key] == :symlog
+            @warn "Plots.jl does not support symlog axis scaling for $key."
+            ctx[key] = :identity
+        end
+    end
+
     ctx[:xscale] == :log ? ctx[:xscale] = :log10 : nothing
     ctx[:yscale] == :log ? ctx[:yscale] = :log10 : nothing
 

ext/GridVisualizePlutoVistaExt.jl

@@ -221,6 +221,13 @@ function scalarplot!(
     PlutoVista = ctx[:Plotter]
     PlutoVista.backend!(ctx[:figure]; backend = ctx[:backend], datadim = 1)
 
+    for key in (:xscale, :yscale)
+        if ctx[key] == :symlog
+            @warn "Plutovista.jl does not support symlog axis scaling for $key."
+            ctx[key] = :identity
+        end
+    end
+
     for ifunc in 1:nfuncs
         func = funcs[ifunc]
         grid = grids[ifunc]

src/dispatch.jl

@@ -386,6 +386,7 @@ function default_plot_kwargs()
         :spacing => Pair(nothing, "Removed from API"),
         :species => Pair(1, "Number of species to plot or number of species in regions"),
         :subplot => Pair((1, 1), "Private: Actual subplot"),
+        :symlog_threshold => Pair(10.0, ":symlog threshold for switching from linear to log scaling. Only relevant for :symlog axis scaling."),
         :title => Pair("", "Plot title"),
         :tetxplane_tol => Pair(0.0, "tolerance for tet-plane intersection in 3D"),
         :vconstant => Pair(false, "Set all arrow length constant in vector plot"),
@@ -395,11 +396,11 @@ function default_plot_kwargs()
         :xlimits => Pair((1, -1), "x axis limits"),
         :xplanes => Pair([prevfloat(Inf)], "3D x plane positions or number thereof"),
         :xlabel => Pair("x", "x axis label"),
-        :xscale => Pair(:identity, "x axis  scale: one of [:log, :identity]"),
+        :xscale => Pair(:identity, "x axis  scale: one of [:log, :identity, :symlog]"),
         :ylimits => Pair((1, -1), "y axis limits"),
         :ylabel => Pair("y", "y axis label"),
         :yplanes => Pair([prevfloat(Inf)], "3D y plane positions or number thereof"),
-        :yscale => Pair(:identity, "y axis  scale: one of [:log, :identity]"),
+        :yscale => Pair(:identity, "y axis  scale: one of [:log, :identity, :symlog]"),
         :zlimits => Pair((1, -1), "z axis limits"),
         :zplanes => Pair([prevfloat(Inf)], "3D z plane positions or number thereof"),
         :zlabel => Pair("z", "z axis label"),

src/pycommon.jl

@@ -436,21 +436,14 @@ function scalarplot!(ctx, TP::Type{T}, ::Type{Val{1}}, grids, parentgrid, funcs)
     ax = ctx[:ax]
     fig = ctx[:figure]
 
+    # activate log scaling
+    ctx[:xscale] == :log && ax.set_xscale("log")
+    ctx[:xscale] == :symlog && ax.set_xscale("symlog", linthresh = ctx[:symlog_threshold])
+    ctx[:yscale] == :log && ax.set_yscale("log")
+    ctx[:yscale] == :symlog && ax.set_yscale("symlog", linthresh = ctx[:symlog_threshold])
+
     pplot = ax.plot
-    if ctx[:xscale] == :log
-        if ctx[:yscale] == :log
-            pplot = ax.loglog
-        else
-            pplot = ax.semilogx
-        end
-    end
-    if ctx[:yscale] == :log
-        if ctx[:xscale] == :log
-            pplot = ax.loglog
-        else
-            pplot = ax.semilogy
-        end
-    end
+
     gridscale = ctx[:gridscale]
     if ctx[:cellwise] # not checked,  outdated
         for icell in 1:num_cells(grid)