[R] Controlling the length of line with abline(lm())

[Greg Snow]

You can use the clipplot function in the TeachingDemos package to limit the range of the line (the 2nd example in the help page shows an example of 3 lines for 3 subgroups of data with each line limited to the x-range of the data).  There is also the clip function in the graphics package (no extra packages need to be installed), but it uses a different interface and getting it to work can be tricky sometimes.

Hope this helps,

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111



> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On Behalf Of Tariq Perwez
> Sent: Wednesday, June 18, 2008 8:09 PM
> To: r-help at r-project.org
> Subject: [R] Controlling the length of line with abline(lm())
>
> Hi
> I just realized that when I use linear regression to draw a
> line through my data points with something like the following:
>
> abline(lm(y ~ x))
>
>
> the length of the line is infinite, i.e., the line goes
> beyond the smallest and the largest data values. This seems
> not very right to me (not to mention it looks unaesthetic). I
> do not mean to imply that the straight-line behavior of my
> system is maintained throughout. I would like to limit the
> length of this line to the range of my data. However, I have
> not been able to figure out how to. Very disconcertingly, I
> found out that all the books that teach statistics using R
> seem to be drawing such infinite length-lines.
> I would appreciate any advice or suggestions. Regards,
>
>
> Tariq
>
>         [[alternative HTML version deleted]]
>
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