[R] controling the size of vectors in a matrix

[Adaikalavan Ramasamy]

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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