[R] how to find the index of points selected from a scatter plot?

[Greg Snow]

I would be very surprised if the x value from locator matched the x
value in the data to the precision needed by ==, and what if 2 points
have the same x-value but different y-values, you would need to also
check the y's.  With appropriate rounding this would work, but would
just be reinventing the identify function (as Peter pointed out).

So if you are happy to reinvent wheels for learning purposes then
locator, which, and rounding (or min)  could teach a lot.  If the
simplest most straight forward solution is sought, then use identify
instead of locator.

On Fri, Aug 31, 2012 at 5:03 PM, Bert Gunter <gunter.berton at gene.com> wrote:
> ?which ##
> as in ix <- which(x==values)
>
> -- Bert
>
> On Fri, Aug 31, 2012 at 2:09 PM, Michael <comtech.usa at gmail.com> wrote:
>
>> Hi all,
>>
>> I am using "locator" to select the points from a scatter plot...
>>
>> This is all fine.
>>
>> But the problem is that the locator only returns the axis values of the
>> selected points.
>>
>> Instead, I would like to get the index of these select points...
>>
>> The axis values are real-values so it's a bit hard for me to directly
>> reverse-engineer the index nubmers..
>>
>> How to do that?
>>
>> Thank you!
>>
>>         [[alternative HTML version deleted]]
>>
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>>
>
>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
> Phone: 467-7374
> Website:
> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.



-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com