Re: plotting question

[Paul Kienzle]

Jonathan Nichols wrote:

> hello all,
>
>    i have a plotting question that i was wondering if you could help 
> with. 
>    i have a set of x,y pairs, each of which has a z value.  i would 
> like to create a 2-D plot where every x,y pair has a point associated 
> with it, whose color indicates the magnitude of the z value. 

If your dataset is uniformly sampled, you can use
an image.  If it is not uniformly sampled, you can
try using griddata from octave-forge to turn it into
an image.

Alternatively, you could try scatter.m:

http://octave.sf.net/index/f/scatter.html

Only use colours 1-8.  If your dataset is
large, don't use the variable marker size
option.

>    ideally, i would like to be able to use the colormap feature so 
> that i can use any color for the points.  if this is possible, how do 
> i tell the plot function to use a color from the colormap?  or is it 
> done with the gset command?
>
>    if this is not possible, i can use the format feature of the plot() 
> fuction which gives me a choice of one of the red, green, blue, cyan, 
> magenta, brown colors.
>
>    one of the methods i have tried is the following:
>
>    plot(x1,y1,color1);
>    hold on
>    plot(x2,y2,color2);
>    plot(x3,y3,color3);
>
> .....
>
>    the problem with this is that it puts a plot legend in the upper 
> right hand corner of the plot.  since there are hundreds of points in 
> this dataset, the entire plot is covered with "line 123" legend text. 
>    if i use the above method, how do i get rid of the legend text?

plot(x,y,[color,";;"])

This is what scatter.m does internally.

Paul Kienzle
address@hidden



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