# Colors in RegionPlot legend

I'm trying to put a common legend for two-row RegionPlot. However, I haven't been able to get the colors in the legend right:

ra = RegionPlot[{y >= x^2 - 4 , y >= x^2 - 4 && y <= 0 }, {x, -10,
10}, {y, -10, +10}]

rb = RegionPlot[{y >= x^2 - 16 , y >= x^2 - 16 && y <= 0 }, {x, -20,
20}, {y, -20, +20}]

Legended[GraphicsRow[{ra, rb}, Spacings -> Scaled[0.4],
Epilog -> Inset["Plot Title", Scaled[{0.5, 0.95}]]],
SwatchLegend[{Blue, Orange}, {"label1", "label2"}]]

Legended[GraphicsRow[{ra, rb}, Spacings -> Scaled[0.4],
Epilog -> Inset["Plot Title", Scaled[{0.5, 0.95}]]],
SwatchLegend[{LightBlue, LightOrange}, {"label1", "label2"}]]

I've also tried to change the colors of the regions. However, as far as I could tell, the declared color applied to the boundaries; the interior was a shade lighter, something I couldn't reproduce in the legend. Any ideas on how to address the problem?

## 1 Answer

How about this one?

ra = RegionPlot[{y >= x^2 - 4, y >= x^2 - 4 && y <= 0}, {x, -10,
10}, {y, -10, 10}, PlotStyle -> {Blue, Orange},
BoundaryStyle -> None];
rb = RegionPlot[{y >= x^2 - 16, y >= x^2 - 4 && y <= 0}, {x, -10,
10}, {y, -18, 10}, PlotStyle -> {Blue, Orange},
BoundaryStyle -> None];
Legended[Labeled[Multicolumn[{ra, rb}],
Style["Plot Title", 15, Bold, FontFamily -> "Helvetica"], Top],
SwatchLegend[{Blue, Orange}, {"label1", "label2"}]]

• It did work! Now, although my application is much more convoluted, this MWE captures the fact that each region is a subset of another. Thus, anyone interested in using this approach should start RegionPlot from the largest set, and then proceed all the way towards the smallest. The order matters here. May 18, 2021 at 18:09