On Jan 23, 2013, at 5:31 PM, David Winsemius wrote:
On Jan 23, 2013, at 7:13 AM, emorway wrote:
The following 1460 x 1460 matrix can be throught of as 16 distinct
365 x 365
matrices. I'm trying to set off-diaganol terms in the 16 sub-
matrices with
indices more than +/- 5 (days) from each other to zero using some
for loops.
This works well for some, but not all, of the for loops. The R
code I"m
using follows. For some reason the third loop below zero's-out
everything
in the sub-quadrant it is targeting, which is readily observable when
viewing the matrix ("View(MAT)").
library(Matrix)
MAT<-matrix(rnorm(1460*1460,mean=0,sd=1),nrow = 1460, ncol = 1460)
The way to do that in a single 365 x 365 matrix is:
Mat <- matrix( 1:(365*365), 365, 365)
Mat[ abs( col(Mat)-row(Mat) ) > 5 ] <- 0
Mat
The way to propagate that pattern is to use rep(), so here is a one-
liner for the task:
MAT[ rep( abs( col(Mat)-row(Mat) ) > 5, 16) ] <- 0
That might not construct the bands in the blocks correctly: This might
be better:
MAT [ kronecker( matrix(1, 4,4), abs( col(Mat)-row(Mat) ) > 5,
FUN="&" ) ] <- 0
--
David.
Didn't test on you gigantuan matrix; used smaller example:
Mat <- matrix( 1:(16*16), 16, 16)
test <- rbind(Mat, Mat)
test[rep( abs( col(Mat)-row(Mat) ) > 2 , 2)] <- 0
test
--
David.
#works great
for (i in 1:365) {
SEQ <- (i - 5):(i + 5)
SEQ <- SEQ[SEQ > 0 & SEQ < 366]
MAT[(1:365)[-SEQ], i] <- 0
}
#works great
for (i in 1:365) {
SEQ <- (i - 5):(i + 5)
SEQ <- SEQ[SEQ > 0 & SEQ < 366]
MAT[(1:365)[-SEQ], i + 365] <- 0
}
#zero's out everything, including main-diagonal and near-main-
diagonal
terms???
for (i in 731:1095) {
SEQ <- (i - 5):(i + 5)
SEQ <- SEQ[SEQ > 730 & SEQ < 1096]
MAT[(731:1095)[-SEQ], i + 365] <- 0
}
View(MAT)
I'm not sure why the third FOR loop above is not leaving the main-
diagonal
and near-main-diagonal terms alone?
--
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http://r.789695.n4.nabble.com/setting-off-diagonals-to-zero-tp4656407.html
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David Winsemius
Alameda, CA, USA
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Alameda, CA, USA
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
