Hi,

matrix has a 2 dimensions.

Is this work:

a<-matrix(rep(c(1,2),c(5,5)),ncol=1)
dim(a)
for (i in 1:10)
{
ifelse(a[i,]==1, a[i,]<-runif(1,3,4.5), a[i,])
}
a

Andrija


On Tue, Mar 8, 2011 at 1:07 PM, dpender <d.pender.1@research.gla.ac.uk>wrote:

> Hi,
>
> I am having some problems using the if statement correctly.  I have used it
> many times previously so I dona't know what is different with this case.
> Here is my problem:
>
> I have a 1X10 matrix of values as follows:
>
> > H.MC <http://h.mc/>
>          [,1]
>  [1,] 4.257669
>  [2,] 7.023242
>  [3,] 4.949857
>  [4,] 5.107000
>  [5,] 4.257669
>  [6,] 4.257669
>  [7,] 4.257669
>  [8,] 4.257669
>  [9,] 4.257669
> [10,] 4.257669
>
> What I want to do is replace all the values if 4.257669 with a random
> number
> between 3 and 4.5.  To do this I have:
>
> H.MC.fin <- matrix(0,10,1)
>
> for (j in 1:10) {
>
> if(H.MC <http://h.mc/>[j] == 4.257669) H.MC.fin[j] <-runif(1,3,4.5) else
> H.MC.fin[j] <-
> H.MC <http://h.mc/>[j]
>
> }
>
> This doesn't seem to do anything and H.MC.fin is the same as H.MC<http://h.mc/>
> .
>
> Does anyone know what I am doing wrong?
>
> Thanks,
>
> Doug
>
>
> --
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>
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