Thanks to David Meyer [david.meyer@ci.tuwien.ac.at] and David Brahm [brahm@alum.mit.edu] who suggested: m[ cbind(index.i, index.j) ] <- vals This works fine for the example I gave. Unfortunately, this approach doesn't extend to using the row and column names to make assignments:
m <- matrix("",ncol=3,nrow=3)
dimnames(m) <- list(c("a","b","c"), c("A","B","C"))
m
A B C a "" "" "" b "" "" "" c "" "" ""
index.i <- c("b","a","c")
index.j <- c("B","A","C")
vals <- c("1","2","3")
m[ cbind(index.i, index.j) ] <- vals
m
b a c B A C "" "" "" "" "" "" "" "" "" "1" "2" "3" "1" "2" "3" This looks like a bug... -Greg
-----Original Message-----
From: David Brahm [mailto:brahm@alum.mit.edu]
Sent: Wednesday, February 20, 2002 5:21 PM
To: gregory_r_warnes@groton.pfizer.com
Cc: r-devel@hypatia.math.ethz.ch
Subject: [Rd] Feature Request: "matrix[1:10,1:10, block=F] <- 1:10"
Gregory R Warnes <gregory_r_warnes@groton.pfizer.com> wrote:
R> m <- matrix("", nrow=3,ncol=3)
R> index_i <- c(2,1,3)
R> index_j <- c(1,3,2)
R> vals <- c("a","b","c")
R> m[ index_i, index_j ] <- vals
but what he wants to get is:
> [,1] [,2] [,3] > [1,] "" "" "b" > [2,] "a" "" "" > [3,] "" "c" ""
Just do this instead:
R> m[ cbind(index_i, index_j) ] <- vals
--
-- David Brahm (brahm@alum.mit.edu)
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