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Re: Transparent ContourPlot - Minor error at the origin

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123797] Re: Transparent ContourPlot - Minor error at the origin
  • From: Syd Geraghty <sydgeraghty at me.com>
  • Date: Mon, 19 Dec 2011 07:22:09 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201112161052.FAA06915@smc.vnet.net>

Heike,

I noticed that the mesh function chosen automatically led to a mis-colouring of a small triangle at the origin which can be corrected by using a MaxRecursion of 7.


ContourPlot[x y^2 + 2, {x, -2, 2}, {y, -2, 2}, PlotRange -> {-10, 10},
  ImageSize -> 600, MaxRecursion -> 7, 
 Method -> {"GridLinesInFront" -> True, 
   "TransparentPolygonMesh" -> True}, 
 ColorFunction -> (Directive[Opacity[.5], ColorData["Rainbow"][#]] &),
  ContourShading -> Automatic, GridLines -> Automatic]

Cheers .... Syd

Syd Geraghty B.Sc, M.Sc.

sydgeraghty at me.com

Mathematica 8.0 for Mac OS X x86 (64-bit) (February 23, 2011)
ReleaseID:    8.0.1.0 (2063982, 2063639)
MacOS X V 10.7.1 Lion 
MacBook Pro 2.33 GHz Intel Core 2 Duo  3GB RAM





On Dec 18, 2011, at 1:34 AM, Heike Gramberg wrote:

> To draw grid lines on top of the plot, you could use the (undocumented) option
> Method->{"GridLinesInFront"->True}, so you could do something like
> 
> ContourPlot[x y^2 + 2, {x, -2, 2}, {y, -2, 2},
> PlotRange -> {-10, 10},
> Method -> {"GridLinesInFront" -> True},
> GridLines -> Automatic]
> 
> If you still want to have a transparent shading, you probably want to set
> Method -> {"TransparentPolygonMesh" -> True} as well which will get rid of the edges of
> the individual polygons. You can combine these two options as follows
> 
> ContourPlot[x y^2 + 2, {x, -2, 2}, {y, -2, 2},
> PlotRange -> {-10, 10},
> Method -> {"GridLinesInFront" -> True, "TransparentPolygonMesh" -> True},
> ColorFunction -> (Directive[Opacity[.5], ColorData["Rainbow"][#]] &),
> ContourShading -> Automatic,
> GridLines -> Automatic]
> 
> Heike
> 
> On 16 Dec 2011, at 11:52, dg wrote:
> 
>> I have been trying to create a contour plot where the contour shading is transparent, so that I can draw gridlines and see them through the contours. I can't seem to figure this one out....
>> 
>> This produces a mess:
>> 
>> ContourPlot[x y^2 + 2, {x, -2, 2}, {y, -2, 2}, PlotRange -> {-10, 10},
>> ContourShading -> {Orange, Opacity[0.5]}]
>> 
> 
> 







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