From: Greg Snow <Greg.Snow_at_imail.org>

Date: Sat, 12 Mar 2011 20:59:29 -0700

Date: Sat, 12 Mar 2011 20:59:29 -0700

If you are always using asp=1 then you can just do something like:

x <- rnorm(100, 1, 5)

y <- rnorm(100, 3, 4)

plot( x,y, asp=1)

r=2

nseg=360

x.cent <- 5

y.cent <- 7

xx <- x.cent + r*cos( seq(0,2*pi, length.out=nseg) ) yy <- y.cent + r*sin( seq(0,2*pi, length.out=nseg) )

lines(xx,yy, col='red')

-- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.snow_at_imail.org 801.408.8111Received on Sun 13 Mar 2011 - 04:04:00 GMT

> -----Original Message-----

> From: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-> project.org] On Behalf Of Allan Kamau> Sent: Saturday, March 12, 2011 1:08 PM> To: r-help_at_r-project.org> Subject: Re: [R] Drawing a circle on an existing graph.>> On Sat, Mar 12, 2011 at 10:22 PM, David Winsemius> <dwinsemius_at_comcast.net> wrote:> >> > On Mar 12, 2011, at 10:56 AM, Allan Kamau wrote:> >> >>> --- On Sat, 3/12/11, Allan Kamau <kamauallan_at_gmail.com> wrote:> >>>> >>>> From: Allan Kamau <kamauallan_at_gmail.com>> >>>> Subject: [R] Drawing a circle on an existing graph.> >>>> To: r-help_at_r-project.org> >>>> Received: Saturday, March 12, 2011, 3:08 AM> >>>> I would like to draw a circle on a> >>>> graph I am plotting in R and use> >>>> the current plot's coordinate system.> >>>> The most basic functionality I am looking for is the> >>>> ability to plot a> >>>> circle on an already existing graph by simply providing the> >>>> xy> >>>> coordinates for it's centre and the radius.> >>>>> >>>> I am also looking for a way to obtain x,y values of a point> >>>> (of a> >>>> circle) by specifying only the origin x,y the angle and> >>>> radius.> >>>>> >>>> Please point me so such a library and perhaps some simple> >>>> one line code.> >>>>> >>>> Allan.> >>>>> >> On Sat, Mar 12, 2011 at 5:28 PM, John Kane <jrkrideau_at_yahoo.ca>> wrote:> >>>> >>> Is this of any use?> >>> http://tolstoy.newcastle.edu.au/R/help/06/04/25821.html> >>>> >>> >> Thank you John, that is what I was looking for.> >> The code does draw a neat circle that is not stretched. After> plotting> >> the circle on an existing plot I notice that the original plot was> >> indeed stretched somehow by approximately some 1:1.1 ratio (I> think).> >> Now I am looking for a way to enforce none stretching in my original> >> graph.> >> > `plot.window` has an `asp` argument that is useful for that purpose.> Most> > plotting with base graphics will pass an asp=1 argument along as part> of the> > `...` arguments,> >> > --> >> > David Winsemius, MD> > West Hartford, CT> >> >> Thank you David, asp=1 argument in my plot function brought about 1:1> aspect ratio to the graph and now the circle sits very neatly within> it. All is well.> John is there another version of your circle drawing code that accepts> values in accordance with the current plot's scale units in place of> the current real distance measurement (inches) units.>> Allan.>> ______________________________________________> R-help_at_r-project.org mailing list> https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide http://www.R-project.org/posting-> guide.html> and provide commented, minimal, self-contained, reproducible code.

______________________________________________ R-help_at_r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.2.0, at Sun 13 Mar 2011 - 04:10:20 GMT.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*