[R] [OT] 'gv' and fractional points

[Deepayan Sarkar]

On 6/15/07, Ted Harding <ted.harding at nessie.mcc.ac.uk> wrote:
> Hi Folks,
>
> This is off-topic R-wise, but it may be close to
> the heart of many R-users, so I think it may be
> the best place to ask!
>
> Users of 'gv' (the "front end" to ghostscript) will
> be aware of the little window which gives you the
> x-y coordinates (in points = 1/72 inch) of the position
> of the "cross-hair" mouse cursor. These coordinates
> are those of the corresponding position on the printed
> page, relative to some origin.
>
> I have often used this to extract numerical values
> for data from graphs in Postscript files (also PDF
> files, after you have converted them to PS). Then
> (veering back on topic ... ) you can submit the
> numerical data to R and try your own analyses on
> these data, and compare with what the article does.
>
> However, this little window only gives the numbers
> in whole points. Say a smallish graphic may print
> out 3 inches wide or high. Then you get precision
> of 1/216 per 3 inches or 0.4% of full scale. This
> can be adequate on many occasions, but can be on
> the coarse side on other occasions.

If you are mostly concerned about small figures, one possibility is

1. zoom out to a level where you're happy with the pixel resolution
2. do a screen capture using 'import'
3. use gimp (which has the same feature, with more units)

gimp can also load PS files directly, with a user supplied zoom factor
at load time, but only one page at a time, AFAICT.

-Deepayan