[R] pch=15 symbol of size=10 mm

[Jim Lemon]

Denis White wrote:

> How do I determine cex in
>
>   points (x, y, pch=15, cex=?)
>
> to get a square whose side length is, say, 10 mm?
>
> thanks

The easy way would be:

points(6,3,pch=15,cex=10/(par("cin")[1]*25.4))

That is, divide your desired width by the current width in inches multiplied by
25.4,

but this won't _really_ give you a 10 mm square.  The hardcopy output you get
depends upon the size of the image you generate (e.g. the "bounding box" in
Postscript).  However, you could fudge it if you always use the same size
output...

Jim

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