Add marker for zero values in scatter plot

src/PlotPFC.jl

@@ -46,16 +46,20 @@ function scatter_branchloads(
 
     ### Scatter branch loads versus each other
     diff = y_bl - x_bl # deviation from ratio 1 for coloring
-    mcolors = pyimport("matplotlib.colors")
-    offset = mcolors.TwoSlopeNorm(
-        vcenter=0, vmin=minimum(diff), vmax=maximum(diff)
-    ) # match diff to values between 0 and 1
+    diff[diff .== 0.0] .= -10 # map exact zero values to -10 for distinct color
+    # mcolors = pyimport("matplotlib.colors")
+    # offset = mcolors.TwoSlopeNorm(
+    #     vcenter=0, vmin=minimum(diff), vmax=maximum(diff)
+    # ) # match diff to values between 0 and 1
     cmap = plt.get_cmap(settings["cmap"])
+    cmap.set_under("tab:green")
     sc = plt.scatter(
         x_bl, y_bl,       
         s = settings["size"],
-        c = offset(diff),
+        c = diff,
+        # c = offset(diff),
         cmap = cmap,
+        vmin = -1.,
         vmax = 1.,
         edgecolors = settings["ec"],
         linewidths = settings["lw"],
@@ -63,8 +67,11 @@ function scatter_branchloads(
     )
 
     ### Add colorbar
-    sm = plt.cm.ScalarMappable(cmap=cmap, offset)
+    sm = plt.cm.ScalarMappable(cmap=cmap, norm=plt.Normalize(-1., 1.))
+    # sm = plt.cm.ScalarMappable(cmap=cmap, offset)
     cbar = plt.colorbar(sm)
+    cbar.ax.plot([-1, 1], [0.0, 0.0], "tab:green")
+    # cbar.add_lines(CS2)
     cbar.ax.set_ylabel(
         L"Difference $y-x$", rotation=-90, va="bottom"
     )