The only way (at least that I know of) to change color is to split
your data and do several scatterplots:
twoway (scatter ... if z>=9, ... mcolor(gs12)) (scatter ... if z>7.5 &
z<9, ... mcolor(gs8)) (scatter ... if z<7.5, ... mcolor(gs4))
This can probably be automated with a ~15 line wrapper program that
takes in z, y, z and the thresholds.
Graphics in R is notably stronger than in Stata.
On Sun, Aug 24, 2008 at 10:42 AM, David Airey
<[email protected]> wrote:
> .
>
> At this page, we see how to change symbol size by using (analytic) weights:
>
> http://www.stata.com/support/faqs/graphics/gph/graphdocs/scatter5.html
>
> e.g.,
>
> webuse census
> scatter death medage [w=pop65p], msymbol(circle_hollow)
>
> Can we change both symbol size and color shading as in the R example below?
>
> -Dave
>
> ###------------------create the test data.frame
> y = c(.4, 1, 2.15, 1.8, 2.7, 2.2, 1.3, .25, 1.1, .1)
> x = c(.35, .4, .41, 1.4, 2.1, 2.25, 2.15, 2.2, 1.45, 1.3)
> z = c(9, 7, 7.5, 7.3, 7, 7.1, 7.75, 9.5, 8, 10)
> d = data.frame(x = x, y = y, z = z)
>
> d$col = gray(.5)
> d$col[d$z>=9] = gray(.2)
> d$col[d$z<7.5] = gray(.7)
> #thikness = sqrt(d$y^2 + d$x^2)
> thikness = abs(d$y) + abs(d$x)
>
>
> ###----------------simple, 2-D plot
> plot(d$x, d$y, pch=19, cex=(d$z-min(d$z)/1.5), xlim = c(-1.5,4), ylim =
> c(-2.5,5), col=d$col)
--
Stas Kolenikov, also found at http://stas.kolenikov.name
Small print: I use this email account for mailing lists only.
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