[Scilab-users] filled contour plot

[Claus Futtrup]

Hi Scilabers

I can explain a bit more. If I double the number in the colormap (from 5 to
10), then contourf doesn't fail (in the previous code example).
Then the contour lines only use the first half of the color map (from blue
to green) ... maybe it would be better if contour-lines where white. Can I
do that, somehow?

Best regards,
Claus

On Sun, Jan 21, 2018 at 3:55 PM, Claus Futtrup <cfuttrup at gmail.com> wrote:

> Dear Scilabers
>
> In my endeavours to plot radiation pattern for loudspeakers, besides polar
> plot, I'm also attemptning to view my data with a sonogram (2D contour
> plot). Here I ask for help to manage the colors of the plot. Here's the
> code (same reduced data as before):
>
> // Test data
> frequencies = [200 2000 20000]; // Hz
> angles = [0 30 60 90 120 150 180]; // degrees - convert to radians!
> mag00 = [69.253448 92.163385 87.414209]; // on-axis freq-response
> mag30 = [68.461357 90.569082 76.073549];
> mag60 = [65.842262 90.745621 74.152067];
> mag90 = [59.420658 80.893365 55.975304];
> mag120 = [52.505173 80.795915 44.363582];
> mag150 = [53.829987 59.793715 42.443964];
> mag180 = [55.650341 73.457973 55.608187];
> magnitudes = [mag00' mag30' mag60' mag90' mag120' mag150' mag180'];
> // 3 freq x 7 angles = 21 data points, put into a matrix.
> // In the complete dataset there's 183 frequencies and 72 angles.
>
> negative_angles = -angles(2:7);
> neg_angle_magnitudes = magnitudes(:,2:7);
>
> angles = [angles negative_angles];
> magnitudes = [magnitudes neg_angle_magnitudes];
> [angles idx] = gsort(angles,'g','i');
> magnitudes = magnitudes(:,idx);
>
> // Plot example:
> contourplt = scf();
> xset("fpf"," "); // Floating Point Format
> contourplt.color_map=jetcolormap(5); // blue = cold, red = hot :-)
> contour2d(frequencies,angles,magnitudes,50:10:90,logflag="ln");
> contourf(frequencies,angles,magnitudes); // FILL with color
> contour2d(frequencies,angles,magnitudes,50:10:90);
> legends(string(50:10:90),1:5,"lr");
>
> P.S. "funny" - I'm plotting contour2d first, because then I can specify
> logflag and the numeric labels goes bye-bye. If I execute contourf first, I
> cannot use log-x-axis. contourf complains that Nax cannot work with
> log-x-axis data, but contourf fills the plot anyway. I then redo the
> contour2d to get my contourlines back (because contourf paints over them).
>
> Help how to get the right colors in the plot would be highly appreciated.
> In particular contourf complains: Colormap too small
>
> Can I manage colormap for contour2d and contourf separately?
>
> Best regards,
> Claus
>
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