| Re: Missing fill colours in contour plot [message #82802 is a reply to message #82801] |
Wed, 16 January 2013 06:47   |
Sir Loin Steak
Messages: 42
Registered: January 2012
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Member |
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On Wednesday, January 16, 2013 2:34:52 PM UTC, David Fanning wrote:
> ljs15@fsmail.net writes:
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>> Right, I've just done some more checking, and when I specify the colour values to range from 0-255 it works, but when I set them to range from 0-250 it doesn't. The two plots are shown at http://www.physics.open.ac.uk/~lsteele/contour2.
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>> In the two plots shown, the left is done using ccol=floor(findgen(ncont)/(ncont-1)*255) and the right is done using ccol=floor(findgen(ncont)/(ncont-1)*250), with ncont=30. So, the only change is going from 255 to 250, with the contours being correct at 255.
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>> Does anyone know why this would be causing a problem?
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> I think you have a fairly odd way of selecting colors and contours,
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> which is causing a mismatch between the contours, the data, and the
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> colors. What happens if you set the contours and colors up this way:
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> minv = Floor(min(array))
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> maxv = Ceil(max(array))
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> ncont = 30
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> clevels = Findgen(ncont) * ((maxv - minv) / ncont) + minv
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> LoadCT, 25, NCOLORS=ncont, BOTTOM=1
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> ccol= Bindgen(ncont)+1B
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> Cheers,
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> David
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> --
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> David Fanning, Ph.D.
>
> Fanning Software Consulting, Inc.
>
> Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
>
> Sepore ma de ni thue. ("Perhaps thou speakest truth.")
Hi David.
The reason for specifying the contours is that the data range from positive to negative values, and I'm using a blue-white-red colour scale to plot (+ve is red, -ve is blue).
In order to make sure white represents 0, I need to set the contour levels to span the maximum range. So if the data had minv = -20 and maxv = +50, I want the contours to range from -50 to +50.
There may be a better way of doing it than what I'm doing though!
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