[R] Simple graphics

[hadley wickham]

> Yes and no. This sort-of does what I want, except that it
> has no precision! After I edit the file.png with a graphic editor,
> I notice that the rectangle does not have 100 x 100 pixels
> in the sides, because the vertices are in weird points (instead of
> (50,50) to (150,150), they are from (53,53) to (146,146))

R graphics are fundamentally vector in nature and you are unlikely to
be able to get pixel level precision with them without considerable
contortions.

I'd recommend you look into some other low level graphics drawing
package.  See for example, ImageMagick and some of the many language
bindings it has.

Hadley