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Curated Data Graphics and Visualization Wolfram Language Geographic Information System

World population density plotted with a logarithmic color scale

Posted 9 years ago

Inspired by Vitaliy's cool maps, I wanted to try a couple myself. I found this plot on Wikipedia and thought I'd give it a try. After figuring out a workaround for a bug in the color function scaling in `GeoRegionValuePlot` described here, this is where I arrived GeoRegionValuePlot[CountryData[] -> "PopulationDensity", ColorFunction -> (ColorData[{"BlueGreenYellow", {6, 0}}][ Log@QuantityMagnitude@#] &), ColorFunctionScaling -> False, GeoBackground -> None, ImageSize -> 1000, PlotLegends -> BarLegend[{(ColorData[{"BlueGreenYellow", {6, 0}}][ Log@QuantityMagnitude@#] &), {.001, 300}}, LegendLabel -> "people/\!\(\*SuperscriptBox[\(km\), \(2\)]\)"]] A few issues I encountered with `GeoRegionValuePlot` were Why is Alaska not considered part of the US? This really detracts from the aesthetics of the map I think. Manually setting either `PlotRange -> {0, 300}` or `PlotRange -> Quantity[ {0,300}, "People"/"Kilometers"^2]` had any effect on the legend, which still went all the way up to the absurd value of 20,000. So I scrapped the automatic legend and created my own.

POSTED BY: Jason Biggs

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Posted 9 years ago

to the second question: it's probably because some (very small countries you cant see on this map) do have population densities that high EntityValue[CountryData[], {"PopulationDensity","Name"}]//Sort {... {Quantity[12686.5, ("People")/("Miles")^2], "Gaza Strip"}, {Quantity[18068.3, ("People")/("Miles")^2], "Hong Kong"}, {Quantity[20119.9, ("People")/("Miles")^2], "Singapore"}, {Quantity[39507.7, ("People")/("Miles")^2], "Monaco"}, {Quantity[54193.3, ("People")/("Miles")^2], "Macau"}}

POSTED BY: Peter Barendse

Posted 9 years ago

Yeah, that Macau really messed up the curve, is why I needed a log scale. I guess I just expected the `PlotRange` and `ColorFunction` to behave like they do in `DensityPlot` or similar. But it doesn't quite, and I can't really find the rhyme or reason to it, GeoRegionValuePlot[{Entity["Country", "Greenland"] -> 1, Entity["Country", "Brazil"] -> 5.5, Entity["Country", "Afghanistan"] -> 20}, PlotRange ->{0, #}] & /@ {5, 8, 10, 30, 1000} So above, the legend follows the specified `PlotRange`, but it didn't for the plot in my post. Weird