Fit elipse to xy scatter

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Fit elipse to xy scatter

DrCJones
Hi,

I know there is a package 'elipse' available but I'm not sure how to use it for my specific implementation.


What I would like to do is fit an elipse to two lines of identity (at right angles to each other), as indicated in the following figure:
http://imageshack.us/photo/my-images/30/poincareplotwip.png/

Conceptually, I'm really struggling to even come up with a way of doing this, let alone an implementation.

Would really appreciate some pointers :)
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Re: Fit elipse to xy scatter

Rolf Turner-3

(1) The ellipse package, according to its DESCRIPTION file, is a package of
``Functions for drawing ellipses and ellipse-like confidence regions''.  
It has
nothing to do with *fitting* ellipses.

(2) What on earth do you mean by ``fit an elipse (sic) to two lines of
identity''?

(3) There are (infinitely) many ellipses that could be associated with a
scatter
plot such as that displayed in the figure you refer.  (E.g. confidence
ellipses or
predication ellipses, one of each for each level of confidence.) You
will have to
be much clearer and much more precise about what you wish to accomplish
in order to get any help.

     cheers,

         Rolf Turner


On 23/07/11 11:44, DrCJones wrote:

> Hi,
>
> I know there is a package 'elipse' available but I'm not sure how to use it
> for my specific implementation.
>
>
> What I would like to do is fit an elipse to two lines of identity (at right
> angles to each other), as indicated in the following figure:
> http://imageshack.us/photo/my-images/30/poincareplotwip.png/
>
> Conceptually, I'm really struggling to even come up with a way of doing
> this, let alone an implementation.
>
> Would really appreciate some pointers :)
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Fit-elipse-to-xy-scatter-tp3688117p3688117.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] 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.

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and provide commented, minimal, self-contained, reproducible code.
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Re: Fit elipse to xy scatter

Dieter Menne
In reply to this post by DrCJones
DrCJones wrote
hat I would like to do is fit an elipse to two lines of identity (at right angles to each other), as indicated in the following figure:
http://imageshack.us/photo/my-images/30/poincareplotwip.png/
http://r-project.markmail.org/thread/kpg3ea665y2ud6cz

or, for a robust version using cov.trob(MASS)

http://markmail.org/thread/ck5clreex47pce4j

Dieter