The merge command should do what you want.
merge(df.1, df.2, by="index")
-------------------------------------
William A. Stewart
Senior Manager, Operational Risk
RBC Financial Group
william.stewart@rbc.com
phone: 416-974-3019
-----Original Message-----
From: s-news-owner@lists.biostat.wustl.edu
[mailto:s-news-owner@lists.biostat.wustl.edu] On Behalf Of Kim Elmore
Sent: 2007, November, 13 12:31 PM
To: S-News
Subject: [S] Adding to a data frame
I have a data frame with entries something like the following:
index value1 value2 value3
1 0.5 3.5 4
1 1.0 4.0 5
1 1.5 5.0 6
1 3.0 3.5 7
2 0.6 3.2 4
2 1.5 3.8 7
2 2.8 3.3 7
3 0.8 4.2 9
etc
I have another data frame that looks like this:
index value4 value5 value6
1 33.4 106.9 78
2 34.5 107.0 88
3 32.8 108.2 90
etc
Keying on the "index" value, I want to merge these two data frames to
get the following:
index value1 value2 value3 value4 value5 value6
1 0.5 3.5 4 33.4 106.9 78
1 1.0 4.0 5 33.4 106.9 78
1 1.5 5.0 6 33.4 106.9 78
1 3.0 3.5 7 33.4 106.9 78
2 0.6 3.2 4 34.5 107.0 88
2 1.5 3.8 7 34.5 107.0 88
2 2.8 3.3 7 34.5 107.0 88
3 0.8 4.2 9 32.8 108.2 90
etc.
I can do this row-by-row using a for loop but that seems terribly
inefficient, especially given that I have about 30-40,000 entries to
process. How can I do this more efficiently? I've tried obvious
approaches, but all of what I dreamed up require that the two data
frames have the same number of rows.
Kim Elmore
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