# Re: [R] controling the size of vectors in a matrix

From: Adaikalavan Ramasamy <ramasamy_at_cancer.org.uk>
Date: Thu, 17 May 2007 11:06:30 +0100

1. Your colnames need 4 elements and not 3
2. Utilize the argument 'n' in your random number generators

Your codes could be simplified as:

```  m <- cbind( treatmentgrp  = sample( 1:2, n, replace=T ),
strata        = sample( 1:2, n, replace=T ),
survivalTime  = rexp( n, rate=0.07 ),
somethingElse = rexp( n, rate=0.02 ) )

```

Regards, Adai

raymond chiruka wrote:
> hie R users
>
> l have the following matrix
> n=20
> m<-matrix(nrow=n,ncol=4)
> colnames(m)=c("treatmentgrp","strata","survivalTime")
> for(i in 1:n) m[i,]<-c(sample(c(1,2),1,replace=TRUE),sample(c(1:2),1,replace=TRUE),rexp(1,0.07),rexp(1,0.02))
>
> print(m)
> 1.l would like to control the size of the treatment variable eg treatment 1=size 5 treatment 2=size 15.
>
> 2. l would also want to control the size of the strata ie in treatment 1 divide the strata in to 2 etc.
>
> 3. For the survival time l would like to have treatment 1-strata 1 using a different rate from treatment 2 -strata 2 etc to generate the survival time.
>
> the program l used above does nt do this so if you can help
>
> thanks
>
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Thu 17 May 2007 - 10:22:35 GMT

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