[R] value replacement in matrices
George, Charles R
Charles.George at dpi.qld.gov.au
Fri Aug 1 08:22:35 CEST 2003
Hello R users
I would like to ask if anyone knows a computationally fast solution to this problem:
I have an original matrix and an index matrix. The original matrix is ca 4000x4000 cells, and the index matrix has 261 unique values. From these, I want to produce a new matrix.
Consider the following simplified example:
Original matrix
1 4 6 5
3 4 8 5
2 4 7 8
9 8 3 6
index matrix
1 5
2 7
3 2
4 5
5 3
6 7
7 5
8 3
9 9
my current code is something like this
for(i in 1:9) {
changeVal <- which(originalMat==indexMat[i,1])
finalMat <- indexMat[i,2]
}
the output would look like this:
Final matrix
5 5 7 3
2 5 3 3
7 5 5 3
9 3 2 7
At the moment it takes a while to process. Does anyone have any suggestions?
reagrds
Robert
********************************DISCLAIMER******************...{{dropped}}
More information about the R-help
mailing list