jim holtman wrote:
> Here is one way of doing it that uses the row and column names:
>
>> # create test data
>> mat1 <- matrix(0, nrow=10, ncol=3)
>> dimnames(mat1) <- list(paste('row', 1:10, sep=''), LETTERS[1:3])
>> mat2 <- matrix(1:3, ncol=1, dimnames=list(c('row3', 'row7', 'row5'), "B"))
>> mat2
> B
> row3 1
> row7 2
> row5 3
>> # create indexing matrix
>> indx <- cbind(match(rownames(mat2), rownames(mat1)), match(colnames(mat2),
>> colnames(mat1)))
>> indx
> [,1] [,2]
> [1,] 3 2
> [2,] 7 2
> [3,] 5 2
>> mat1[indx] <- mat2
>> mat1
> A B C
> row1 0 0 0
> row2 0 0 0
> row3 0 1 0
> row4 0 0 0
> row5 0 3 0
> row6 0 0 0
> row7 0 2 0
> row8 0 0 0
> row9 0 0 0
> row10 0 0 0
>
>
> On Nov 12, 2007 4:54 PM, Martin Waller <[EMAIL PROTECTED]> wrote:
<snip>
OK - I see that, and thanks for your response, but (and excuse my
ignorance, less than 2 months in R...) can you help me to see why this
is 'better' (whatever that means, if anything)? From a newbie (at least
my) POV, it seems less clear than my original solution. Again, please
bear in mind I am relatively new so please be patient if I'm not seeing
something that's obvious to yourself. I have a genuine desire to learn.
Martin
______________________________________________
R-help@r-project.org mailing list
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.
