Re: Object graphics color scattergram

[davidf(at)dfanning.com (David Fanning)]

Jeffrey R. Hall (jeffrey.r.hall@jpl.nasa.gov) writes:
> 
> In IDL object graphics, how does one do a scatter plot where 
> the points are colored by some set of values?  Here is an 
> example using direct graphics:
> 
> DEVICE,PSEUDO=8
> seedx		= !pi
> seedy		= !pi ^ 2
> x		= BYTSCL(RANDOMU(seedx, 100, GAMMA=1))/255.0
> y		= BYTSCL(RANDOMN(seedy, 100, GAMMA=1))/255.0
> z		= BYTE( x * 255 )
> LOADCT,15
> PLOTS,x,y,COLOR=z,PSYM=1,LINESTYLE=6
> 
> I have tried IDLgrPlot with and w/o IDLgrSymbol, and also 
> IDLgrPolyline.  Lines can be colored, even faded from one 
> vertex to the next.  But if the lines are omitted then no 
> points are drawn, and if IDLgrSymbol is used then they are 
> all the same color.
> 
> Plus, I need this to be in 24 bit color rather than PSEUDO=8.

I think you just didn't happen onto the correct sequence
of polylines and symbols. Here is an example of an
object graphics scatterplot that I cobbled together
some time ago from my SIMPLE_SURFACE code.

   ftp://ftp.dfanning.com/pub/dfanning/outgoing/misc/scatter_surface.pro

Cheers,

David

-- 
David Fanning, Ph.D.
Fanning Software Consulting
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