Colors chosen for ListPlot, etc., in v. 6
- To: mathgroup at smc.vnet.net
- Subject: [mg88914] Colors chosen for ListPlot, etc., in v. 6
- From: Curtis Osterhoudt <cfo at lanl.gov>
- Date: Wed, 21 May 2008 14:49:51 -0400 (EDT)
- Organization: LANL
- Reply-to: cfo at lanl.gov
Hi, all, I was curious about the colors used automatically for multiple lists in graphics such as ListPlot. I know that it looks as though the colors are reused after about four datasets, but I wanted to test this, so I cobbled together a quick set of commands. It turns out that the colors are not reused, but it's hard to see on smallish plots: (* Create a plot with many data sets so we may include a lot of colors: *) g = ListPlot[(Range[10]*#1 & ) /@ Range[10, 0.1, -0.1], PlotStyle -> PointSize[0.02]] (* A function to extract the hues returned in a graphics object: *) ColorsFromGraphics[graphics_] := Level[Cases[graphics, __Hue, Infinity], {-2, -2}] (* colors used in our plot 'g': *) cols = ColorsFromGraphics[g] (* it turns out that all of the points have the same saturation and brightness, but many more hues appear than just four: *) hues = cols /. Hue[a__] :> (First@{a}) ListPlot[hues] (* note that in the ListPlot of hues, the first four hues wrap around the range {0, 1} quite nicely, but when you get to the fifth hue, it falls quite close to the first one, etc. *) (* The hues have a constant offset, sequentially added, presumably so that they wrap around the "hue space" without repeating themselves: *) ListPlot[Differences@hues] (* but I'm not sure where the chosen number comes from -- it looks as though it's chosen to be a "maximal irrational", so that the hues don't repeat, and the same number shows up when perusing the scientific literature about Hausdorff dimensions and so on in physical systems. Can anyone shed some light on it? *) Cheers, C.O. -- ========================================================== Curtis Osterhoudt cfo at remove_this.lanl.and_this.gov PGP Key ID: 0x4DCA2A10 Please avoid sending me Word or PowerPoint attachments See http://www.gnu.org/philosophy/no-word-attachments.html ==========================================================