Re: R-beta: image(x,y,z)?

Bill Simpson (wsimpson@uwinnipeg.ca)
Tue, 28 Apr 1998 11:30:12 -0500 (CDT)


Date: Tue, 28 Apr 1998 11:30:12 -0500 (CDT)
From: Bill Simpson <wsimpson@uwinnipeg.ca>
Subject: Re: R-beta: image(x,y,z)?
In-Reply-To: <Pine.SUN.3.95.980428084934.6577B-100000@chekov>

Thanks very much Thomas!  Your solution works well!

> > I can get at data$x, data$y, data$z. I want to do an image plot.  Ideally
> > image (or a relative of image) would accept the vectors data$x, data$y,
> > data$z as arguments. (After all, if you can do plot(x,y) on vectors x and
> > y, why can't you do image(x,y,z) on vectors x, y, and z?) However it
> > doesn't work like that.
> 
> The real reason is that it isn't written that way.  There is a good
> rationalisation, though.  image() is a surface plot, not a 3-d
> scatterplot, and so it is necessary that z is defined at every point on
> the x,y grid (otherwise we don't know what color to plot). This is hard to
> ensure when you have image(x,y,z) for vectors
OK I get it.
I guess it would be possible to use x,y,z vector inputs (all same length)
as scatterplot; where is z is not defined at some (x,y), the colour of
that cell could be white or black. One could think of this plot as a
picture of a marked spatial point process if most of the cells are empty.
I am not saying this would necessarily make sense as image(), but maybe as
scatterimage().

Thanks again.

Bill

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