Re: [R] how to generate a column based on other columns in a data frame

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Mon, 11 Feb 2008 12:04:41 -0500

Assuming this data frame:

DF <- data.frame(X = c(36.435, 36.435, 36.435, 35.329, 35.329,
36.431, 36.431, 35.421, 35.421, 35.421), Y = c(30.118, 30.118,
30.118, 29.657, 29.657, 30.111, 30.111, 29.797, 29.797, 29.797))

# Try this:
DF$site <- as.numeric(factor(interaction(DF$X, DF$Y)))

If X and Y can vary slightly while still referring to the same site then round them first to k decimal places first. See ?round

On Feb 11, 2008 11:30 AM, Weidong Gu <wgu_at_uab.edu> wrote:
> HI,
>
>
>
> I am working on a data set with multiple collections of mosquitoes at
> sampling sites. Each row represents a collection of individual samples
> with coordinates for each collection.
>
> ... X, Y,...
>
> 1 36.435 30.118
>
> 2 36.435 30.118
>
> 3 36.435 30.118
>
> 4 35.329 29.657
>
> 5 35.329 29.657
>
> 6 36.431 30.111
>
> 7 36.431 30.111
>
> 8 35.421 29.797
>
> 9 35.421 29.797
>
> 10 35.421 29.797
>
>
>
> Unfortunately, there is no 'site' entry. I would like to add a column of
> 'site' based on the coordinates of samples so that samples from the same
> sites have the same site ID like S1, S2,....
>
>
>
> How to do this in R way? Thanks.
>
>
>
>
>
> Weidong Gu,
>
> Department of Medicine
> University of Alabama, Birmingham
> 1900 University Blvd., Birmingham, Alabama 35294
> Email: wgu_at_uab.edu
> PH: (205)-975-9053
>
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> 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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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. Received on Mon 11 Feb 2008 - 17:09:17 GMT

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