Sv: [R] Using locator() to digitise

[(Ted Harding)]

On 21-Mar-05 Sixten Borg wrote:
> Hi,
> Splus allows pasting a graphics object into the plotting
> window, which makes it possible to do what you describe below.
> Now I use R which doesn't seem to allow pasting the picture
> into the graphics window, so I copy the graph onto a transparency 
> sheet, and stick it onto my screen using tape. The coordinates
> need to be converted to make sense (as you describe).
> 
> My methodology with the transparency has a "stoneage" appearance, but
> it works quite well, if I may say so myself.

Hi Sixten,

Such things often work well! You take me back many years to
my earliest digitising, using a flat-bed pen plotter.

I bought a cheap little "pocket microscope" (the top and
bottom lenses folded out from the upright), plucked two
hairs from my head, and fixed these as *literal* cross-hairs
on the lower lens with sellotape. To use this, I would
remove the pen from its holder on the plotter arm and attach
the microscope to the pen holder with a rubber band. The
sheet to be digitised was laid on the plotter bed in the
usual way.

I then wrote a program (BASIC for CP/M) which would move
the pen-holder under control of the arrow-keys on the
computer, and keep an internal record of the point moved to.
Pressing "Return" would store the plotter coordinates of
the current point in an array.

Any other anecdotes, anyone?

Best wishes,
Ted.


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Date: 21-Mar-05                                       Time: 09:55:58
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