Re: [R] Merging data

From: Chuck Cleland <>
Date: Thu 23 Feb 2006 - 05:21:20 EST

Brian Perron wrote:
> Hello all,
> I am fairly new to R and am trying to bring together data from multiple sources. Here is one problem that I cannot seem to crack Ė I hope somebody can help. Let me simplify the problem: Letís say I have two datasets: DATA1 and DATA2. I would like to work with all the cases in DATA2. I have additional variables on these cases in DATA1, which is a larger data set with many additional cases. I know how to merge data sets if the datasets contain the same cases. However, I want to eliminate all the cases from DATA1 that are not present in DATA2 and then merge. The CASEID is my matching variable, and there are no duplicate variable names.
> Any guidance would be greatly appreciated.

Take closer look at the all.x and all.y arguments in ?merge. Does this give what you want?

merge(DATA1, DATA2, by="CASEID", all.x=FALSE, all.y=TRUE)

Chuck Cleland, Ph.D.
NDRI, Inc.
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Received on Thu Feb 23 05:29:29 2006

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