[R] Transform data for repeated measures

Bert Gunter gunter.berton at gene.com
Fri Aug 28 01:51:00 CEST 2009

I suspect reshape() is the function you're looking for; there is also a
reshape package that you might prefer.

It's also quite easy to do this in base R using unlist() and some indexing
with rep, but that may be more than you care to deal with.

Bert Gunter
Genentech Nonclinical Biostatisics

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Richardson, Patrick
Sent: Thursday, August 27, 2009 4:37 PM
To: r help
Subject: [R] Transform data for repeated measures

I have a dataset that I'm trying to rearrange for a repeated measures

It looks like:

patient basefev1 fev11h fev12h fev13h fev14h fev15h fev16h fev17h fev18h
201     2.46   2.68   2.76   2.50   2.30   2.14   2.40   2.33   2.20    a
202     3.50   3.95   3.65   2.93   2.53   3.04   3.37   3.14   2.62    a
203     1.96   2.28   2.34   2.29   2.43   2.06   2.18   2.28   2.29    a
204     3.44   4.08   3.87   3.79   3.30   3.80   3.24   2.98   2.91    a

And I want to make it look like:

Patient  FEV  time  drug
201         2.46    0         a
201         2.68    1         a
201         2.76    2         a
201         2.50    3         a

And so on . . . . . There would be 9 "time" and drug is a factor variable. 

I know there is a way to do this in R but I cannot remember the function.
I've looked at the transpose function in (base) but that doesn't seem to be
what I want. Can something like this be done easily from within package
functions or would it require writing something custom? Another program
would use something like the transpose procedure, but I'm trying to stay
away from that program.



R version 2.9.2 (2009-08-24) 

LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

attached base packages:
[1] grDevices datasets  tcltk     splines   graphics  stats     utils
methods   base     

other attached packages:
[1] svSocket_0.9-43 svMisc_0.9.48   TinnR_1.0.3     R2HTML_1.59-1
Hmisc_3.6-1     survival_2.35-4

loaded via a namespace (and not attached):
[1] cluster_1.12.0  grid_2.9.2      lattice_0.17-25 tools_2.9.2
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