[R] "user units" in plotrix

Murat Tasan mmuurr at gmail.com
Wed Jan 23 05:12:27 CET 2013

oooooo, sounds like exactly what i want!


On Tue, Jan 22, 2013 at 4:13 PM, Greg Snow <538280 at gmail.com> wrote:
> If you want to convert between different units using base graphics then look
> at the grconvertX and grconvertY functions (in the graphics package).  These
> functions will convert from/to user coordinates, inches, device, figure, and
> plot coordinates.  So you could use grconvertX to  find out what user value
> on the x scale to give to draw.circle that would then generate a circle with
> a given size in inches, or relative to the device, figure, or plotting
> region.
> On Sun, Jan 20, 2013 at 2:59 PM, Murat Tasan <mmuurr at gmail.com> wrote:
>> hi all - i'm having some difficulty figuring out how to convert
>> between "user units" (which i can't find a definition for in the
>> plotrix package) and either (a) device units (e.g. inches with PDFs)
>> or (b) user coordinates along any particular axis.
>> as an example, suppose i set up a PDF device with inches, the device
>> has both outer and inner magins, and the plot region has drastically
>> different x and y coordinate ranges (e.g. xlim = c(0, 1), ylim =  c(0,
>> now i'd like to draw.circle(...) but i can't figure out what units the
>> radius argument takes.
>> "user units" doesn't appear to be inches in this case, and it it
>> corresponds to user coordinates, i don't know which axis' scaling is
>> to be used as the reference.
>> ideally, one would be able to specify the radius in user coordinates
>> while specifying _which_ axis to use as the standard (e.g. an axis =
>> "y" or axis = "x" argument).
>> getFigCtr(...) can help in figuring this out, but its argument takes
>> the relative position of the "figure" region, rather than the "plot"
>> region, which is more apt for properly placing shapes.
>> i know the grid package has extensive unit conversion code, but i'm
>> trying to update a series of figures using only base graphics...
>> i can't seem to find a rigorous definition of "user units" anywhere in
>> the plotrix package.
>> anyone know of where i can find this info?
>> cheers,
>> -m
>> ______________________________________________
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> --
> Gregory (Greg) L. Snow Ph.D.
> 538280 at gmail.com

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