That's probably a stupid question, but I'm looking for a low-level command which plots ellipse, specifying only center and deformation axes. The purpose is to illustrate bivariates gaussians with 2D .95 confident levels without using any specific library. Thanxs for your help, Guillaume
how to draw an ellipse
5 messages · Ben Bolker, Romain Francois, Barry Rowlingson +1 more
Guillaume Allain <guillaume.allain <at> cbconseil.com> writes:
That's probably a stupid question, but I'm looking for a low-level command which plots ellipse, specifying only center and deformation axes. The purpose is to illustrate bivariates gaussians with 2D .95 confident levels without using any specific library. Thanxs for your help, Guillaume
I don't know exactly why you want to avoid "using any specific
library", but the ellipse package (sic) would seem to do what
you want pretty conveniently ...
cheers
Ben Bolker
Le 18.08.2005 15:45, Guillaume Allain a ??crit :
That's probably a stupid question, but I'm looking for a low-level command which plots ellipse, specifying only center and deformation axes. The purpose is to illustrate bivariates gaussians with 2D .95 confident levels without using any specific library. Thanxs for your help, Guillaume
Hello,
Why don't you want to use any specific library ? You can't reinvent the
wheel !!
There is a package ellipse on CRAN which will do what you are looking for.
Have you tried
> RSiteSearch("ellipse")
Cheers,
Romain
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Romain Francois wrote:
Why don't you want to use any specific library ? You can't reinvent the wheel !!
True, but Madonna is always reinventing herself...
There is a package ellipse on CRAN which will do what you are looking for. Have you tried
> RSiteSearch("ellipse")
its simple geometry really: > theta=seq(0,2*pi,len=100) > e=1.5 > r=3 > x=e*r*cos(theta) > y=r*sin(theta) > plot(x,y,asp=1) rotate with: > phi=pi/4 > xr=x*sin(phi)+y*cos(phi) > yr=-x*cos(phi)+y*sin(phi) > plot(xr,yr,asp=1) or something. Wrap that up into a function and you're done. This is off-the-cuff, I've probably messed something up. So use one prepared earlier from a library... Baz
Congratulations guys, you made my day better and funnier! Le 18 ao??t 05, ?? 17:31, Barry Rowlingson a ??crit :
Romain Francois wrote:
Why don't you want to use any specific library ? You can't reinvent the wheel !!
True, but Madonna is always reinventing herself...
There is a package ellipse on CRAN which will do what you are looking for. Have you tried
> RSiteSearch("ellipse")
its simple geometry really:
> theta=seq(0,2*pi,len=100) > e=1.5 > r=3 > x=e*r*cos(theta) > y=r*sin(theta) > plot(x,y,asp=1)
rotate with:
> phi=pi/4 > xr=x*sin(phi)+y*cos(phi) > yr=-x*cos(phi)+y*sin(phi) > plot(xr,yr,asp=1)
or something. Wrap that up into a function and you're done. This is off-the-cuff, I've probably messed something up. So use one prepared earlier from a library... Baz
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