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)
#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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On 23-01-2013, at 16:13, emorway <emorway at usgs.gov> 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) > > #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?Because -SEQ in the last expression is not referencing the correct elements. The first element of (731:1009) has index 1 and not 731. So as far as I can see the last expression should be something like MAT[(731:1095)[-(-730+SEQ)], i + 365] <- 0 Berend
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 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? > > > > -- > View this message in context: http://r.789695.n4.nabble.com/setting-off-diagonals-to-zero-tp4656407.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at 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.David Winsemius Alameda, CA, USA