R help - May 2006 - how to get the data in a circle

I want to get the data in a circle from a large square plot.

If the data includes only two columns or more columns which is number style,
I can do it.
But if the data includes other columns which is not number style (e.g.
species name), I donot know how to do it. And I donot want to delete the
columns because it is useful to me.
e.g.          species    x      y
                    a         12    20
                    b         20    50
                    c         14    25
                    ...        ...    ...

Thanks!

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Assuming your data frame is called dat something like
dat[(dat$x-a)^2+(dat$y-b)^2<=k,]
should work I think.


On 5/25/06, zhang jian <jzhang1982@gmail.com>
wrote:
>
> I want to get the data in a circle from a large square plot.
>
> If the data includes only two columns or more columns which is number
> style,
> I can do it.
> But if the data includes other columns which is not number style (e.g.
> species name), I donot know how to do it. And I donot want to delete the
> columns because it is useful to me.
> e.g.          species    x      y
>                     a         12    20
>                     b         20    50
>                     c         14    25
>                     ...        ...    ...
>
> Thanks!
>
>         [[alternative HTML version deleted]]
>
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