[R] matrix problem

[Charles C. Berry]

On Sat, 4 Jul 2009, William Simpson wrote:

> Can anybody please tell me a good way to do the following?

Not sure how you want cases like x = 1:3, nrow=2 , ncol=7 to be handled, 
but for the example you give, this works:

mat <- matrix(0,nr=nrow,nc=ncol)
indx <- outer(
 		seq( from=0, length=length(x) ),
 		seq( from=1, by=nrow+1, length=ncol ), "+" )
mat[ indx ] <- x


HTH,

Chuck

>
> Given a vector, number of rows and number of columns, return a matrix
> as follows. Easiest to give an example:
>
> x=c(1,2), nrow=5, ncol=4
>
> return the matrix:
>
>   1 0 0 0
>   2 1 0 0
>   0 2 1 0
>   0 0 2 1
>   0 0 0 2
>
> Thanks very much for any help!
> Bill
>
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Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901