[R] Reshape of repeated measures data

[Jesus Frias]

Dear R-helpers,

	I am trying to reshape a data frame that is in a wide format into a long
format one. I have come across the reshape() function, but I have been very
successful using it.

As an example:

ll <-
data.frame(time.1=seq(0.1,1,length=10),L1=rnorm(10),time.2=c(seq(1,7),rep(NA
,3)),R2=c(rnorm(7),rep(NA,3)),time.3=c(seq(1,1.5,length=3)+5,rep(NA,7)),M3=c
(rnorm(3),rep(NA,7)))

which gives me
> ll
   time.1          L1 time.2         R2 time.3         M3
1     0.1 -0.41682731      1 -0.6734289   6.00 -1.7197765
2     0.2  0.45803536      2 -1.7629712   6.25 -0.1756395
3     0.3  0.70046943      3  1.0004967   6.50 -0.6492431
4     0.4 -0.44064572      4 -1.9410689     NA         NA
5     0.5 -0.16925252      5  1.3035123     NA         NA
6     0.6 -0.06501635      6  1.5709351     NA         NA
7     0.7  0.50151676      7  0.1625204     NA         NA
8     0.8 -0.78538134     NA         NA     NA         NA
9     0.9 -0.08774319     NA         NA     NA         NA
10    1.0  1.23420424     NA         NA     NA         NA
>

I have some NA data given that different subjects have different number of
measures and the rate of measurements is different between subjects.

I would like to have a data frame with three variables: 1) time 2) Measure
3) Subject of the form

time	Measure 	Subject
0.1	-0.41682731	L1
...	...		...
6.50 -0.6492431	M3


I have tried with reshape and the closest I've got to it was,

reshape(ll,idvar="Time",varying=list(names(ll)),v.names="Strain",timevar="ID
",direction="long")


Could anybody give me some help?

thanks in advance,

Jesus

--------------------------------------------------------------
Jesús María Frías Celayeta
School of Food Sci. and Env. Health.
Faculty of Tourism and Food
Dublin Institute of Technology
Cathal Brugha St., Dublin 1. Ireland
t +353 1 4024459 f +353 1 4024495
w www.dit.ie/DIT/tourismfood/science/staff/frias.html
--------------------------------------------------------------


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