Re: [R] how do I "relate" tables in R?

From: John Fox <jfox_at_mcmaster.ca>
Date: Sat 11 Feb 2006 - 14:13:18 EST


Dear Jeff,

Assuming that the column named "z" in the matrix data2 already exists and has arbitrary content (such as 0's or NA's), how about the following?

data2[,"z"] <- data1[data2[,"ID"], "z"]

I hope this helps,
 John



John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Jeffrey Moore
> Sent: Friday, February 10, 2006 9:23 PM
> To: r-help@stat.math.ethz.ch
> Cc: colchero@duke.edu
> Subject: [R] how do I "relate" tables in R?
>
> Hi all,
>
> I'm new to the list...pretty new at learning to code in R...
>
> Is there a way to relate 2 different arrays in R?
>
> Hypothetical example:
>
> data1
> ID z
> 1 100
> 2 250
> 3 75
> 4 12
> 5 89
>
> data2
> ID z
> 1
> 1
> 1
> 1
> 2
> 3
> 4
> 3
> 4
> 5
> 5
> 5
> etc.
>
> Goal is to fill column z in data2 with appropriate z-values
> from data1 that correspond to a given ID.
>
> I'm looking for something akin to a relational database, or a
> lookup table in Excel.
>
> I can construct a simple for-loop (with if else statement) to
> fill the z-column in data2, but in my case data2 is 150,000
> records long, so this approach is not efficient.
>
> Thanks for any help
> Jeff
>
> ******************************************
> Jeffrey Moore, Ph.D.
> Postdoctoral Research Scientist
> Duke Center for Marine Conservation
> Duke University Marine Laboratory
> 135 Duke Marine Lab Road
> Beaufort, NC 28516
> Phone: (252) 504-7653
> Fax: (252) 504-7689
> Email: jemoore@duke.edu
> *****************************************
>
>
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>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Feb 11 14:17:17 2006

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