Hi Laura,
The function merge() works well, but another elegant to do it would
involve match().
(Assuming your data.frame object is called x)
x$motherAge <- with(x, age[match(mothers.I.D,I.D)])
Cheers,
--
*Luc Villandré*
/Biostatistician
McGill University Health Center -
Montreal Children's Hospital Research Institute/
John Kane wrote:
x <- "I.D age 'MID'
01 5 03
02 6 06
03 16 NA
04 8 06
05 3 NA
06 17 NA"
xx <- read.table(textConnection(x), header=TRUE); xx
closeAllConnections()
ag1 <- xx[, c(1,2)] ; ag1
ag2 <- xx[, c(1,3)] ; ag2
names(ag2[2]) <- "I.D"
merge(ag1,ag2, by="I.D")
--- On Fri, 6/26/09, Kubasiewicz, Laura <laura.kubasiewic...@imperial.ac.uk>
wrote:
From: Kubasiewicz, Laura <laura.kubasiewic...@imperial.ac.uk>
Subject: [R] Matching data to a new column
To: "r-help@r-project.org" <r-help@r-project.org>
Received: Friday, June 26, 2009, 6:55 AM
Hi all,
I wonder if anyone can help,
I have a dataframe with columns for...
'I.D' 'age' 'mothers I.D'
01 5
03
02 6
06
03 16 NA
04 8
06
05 3
NA
06 17 NA
I need to create a new column for 'mothers age' which puts
the age of the individual with 'mothers i.d' into the row
for her offspring (so individual 01 would have 16 in the
mothers age column, as thats the age of individual 03)
Hope that makes sense, any help appreciated,
Thanks
Laura
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