On 07/18/2012 10:11 PM, Jim Lemon wrote:
On 07/18/2012 09:42 PM, Sarah Goslee wrote:
On Wed, Jul 18, 2012 at 6:42 AM, Jim Lemon<j...@bitwrit.com.au> wrote:
On 07/18/2012 08:02 PM, Stuart Leask wrote:
Hi there.
I have been plotting some circles using 'symbols', with radii
representing
my data, but the radii looked incorrect.
It seems to happen with a single circle too:
Symbols ( 0, 0, circles = 40, xlim = c(-40, 40), ylim= c(-40, 40))
If I put a ruler up to my monitor (technology!) to compare the radius
with the axes, the circle isn't radius 40; it is closer to 15...
I suspect there is a simple answer.
Hi Stuart,
The answer does not appear to be simple. While the documentation for
symbols
says that the "inches" argument controls the size of the circles, it
appears
to do so with reference to the user units of the plot, not to that
quaint
unit descending from the twelfth part of someone's foot. So, whatever
numbers you pass as "circles" seem to be scaled to a maximum
dimension of
whatever "inches" is in user units, at least on the x11 graphics device.
From ?symbols:
If inches is FALSE, the units are taken to be those of the appropriate
axes.
Is that not what's wanted here?
Sarah
My interpretation was that Stuart wanted circles with radii that were
the stated value of the "circles" argument in user units. As the
"inches" argument is TRUE (1) by default, it only seems to serve as a
scaling factor for the values of the "circles" argument. So, the
combination of "circles=40" and "inches=1" yields a circle with a radius
of 1 user unit. When I reran the example with "inches=0.5", I got
circles with a maximum radius of 0.5 user units. I haven't tested this
on any device other than x11.
Jim
Oops, I just realized that I left out saying that you were correct.
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