From help-octave-request at bevo dot che dot wisc dot edu Thu Dec 20 13:23:52 2001
Subject: Re: scatter-plotting by color
From: John Day <jday at csihq dot com>
To: help-octave at bevo dot che dot wisc dot edu
Date: Thu, 20 Dec 2001 14:15:35 -0500

Paul,

Thanks for the tips. But I coudn't get it to run. hsv(), eopen(), 
eglobar(), eaxes() etc are all undefined on my system. Do I need some 
special toolbox for this?

I'm running Octave version 2.1.33 (i586-pc-cygwin).

-jday

At 12:22 PM 12/20/01 -0500, Paul Kienzle wrote:
>AFAIK, gnuplot doesn't have fine grained color control, so you might have
>trouble with this.  I don't know about plplot.
>
>Here's a possibility:
>
>         # generate some data
>         x = rand(30,1);
>         y = rand(size(x));
>         C = rand(size(x));
>         # define a colormap that uses different colors for all its points
>         map=hsv(64);
>         map(1,:)=[1,1,1];
>         colormap(map);
>         # convert your x,y coordinates to image coordinates
>         xi = 1+round((x-min(x))/(max(x)-min(x))*399);
>         yi = 1+round((y-min(y))/(max(y)-min(y))*399);
>         # use implicit sparse->full conversion to build an image array
>         # use conv2 to spread spread the points out a bit (ones(5) makes
>         # them into a 5x5 square, but you could easily define another shape
>         matrix = conv2(sparse(xi,yi,C,400,400),ones(5),'same');
>         # if we had a proper image viewer, we could define the x and y
>         # axes as well:
>         xstep = linspace(min(x),max(x),400);
>         ystep = linspace(min(y),max(y),400);
>         imagesc(xstep,ystep,matrix);
>         # or if you have epsTk:
>         eopen("scatter.ps");
>         eglobpar;
> 
>eaxes([min(x),(max(x)-min(x))/10,max(x)],[min(y),(max(y)-min(y))/10,max(y)]);
>         eimagesc(matrix,map,'e');
>         eclose
>         eview
>
>Paul Kienzle
>pkienzle at users dot sf dot net
>
>On Wed, Dec 19, 2001 at 07:24:59PM -0500, John Day wrote:
> > I have a file of 3-tuples (X,Y,C), where C is an integer 1-16, which I 
> want
> > to scatter-plot, X by Y with C determining the color of the plotted dots.
> >
> > Does anyone know or have a ready-made function to do this? I don't care
> > what the colors are as long as they are unique for each value of C.
> > Different-shaped dots will do if we run out of colors.
> >
> > Thanks,
> > John Day
> >
> >
> >
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> >
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