[R] he^lp on "stack" function

[F Z]

In the future please be a little more specific with your questions. i.e. 
give us an example of your data  the way it looks now and the way you want 
it to look.

I think what you want is something like:

time<-seq(as.Date("2005/1/1"), as.Date("2005/1/10"), "days")
age<-round(runif(10,30,50))
measure<-rnorm(10)
mydat<-data.frame(time=time,age=age,measure=measure) #creates a data frame 
with your 3 #variables

         time age    measure
1  2005-01-01  48 -1.2873181
2  2005-01-02  50  0.5776001
3  2005-01-03  44  0.1892008
4  2005-01-04  38  0.4981651
5  2005-01-05  49 -1.7591745
6  2005-01-06  37 -0.8898464
7  2005-01-07  30  0.7528217
8  2005-01-08  46 -1.2421763
9  2005-01-09  39 -0.9333667
10 2005-01-10  32  1.2086509

#suppose you only want patients older than 40
Older40<-mydat[age>=40,c(1,3)]
        time    measure
1 2005-01-01 -1.2873181
2 2005-01-02  0.5776001
3 2005-01-03  0.1892008
5 2005-01-05 -1.7591745
8 2005-01-08 -1.2421763

Is this what you wanted to do?

Francisco


>From: "" <combe at b3e.jussieu.fr>
>To: "" <R-help at stat.math.ethz.ch>
>Subject: [R] he^lp on "stack" function
>Date: Thu,  3 Feb 2005 18:10:24 +0100
>
>
>
>
>Excuse me.
>I don't understant how to use the function "stack".
>I'm not sure to know the good syntax.
>
>I've got a data witch column names are the time when the mesures was done 
>and
>an
>other who indicates the age of the subjetcs.
>I would like to do a new matrix with patients older than a value and the 
>new
>matrix will contain in the first column the time of the mesures and in the
>second th evalue of the mesure.
>
>Could you help me please ?
>
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