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

[Jeffrey Moore]

thanks, Andy and John, for suggestions.
worked great.
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 at duke.edu
*****************************************

-----Original Message-----
From: John Fox [mailto:jfox at mcmaster.ca] 
Sent: Friday, February 10, 2006 10:13 PM
To: 'Jeffrey Moore'
Cc: colchero at duke.edu; r-help at stat.math.ethz.ch
Subject: RE: [R] how do I "relate" tables in R?

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 at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Jeffrey Moore
> Sent: Friday, February 10, 2006 9:23 PM
> To: r-help at stat.math.ethz.ch
> Cc: colchero at 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 at duke.edu
> *****************************************
>  
> 
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> 
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