Hi, I have a 5 columns x 4 rows matrix and would like to add a diagonal of zeros so that I end up with a 5x5 matrix. x <- matrix(1:20, 4,5) what is the easiest way to accomplish this in R? thanks for any suggestions!
x <- matrix(1:20, 4,5) xx <- matrix(0, nrow=dim(x)[2], ncol=dim(x)[2]) xx[upper.tri(xx)] <- x[upper.tri(x)] xx[lower.tri(xx)] <- x[lower.tri(x, diag=TRUE)] On Sat, Aug 3, 2013 at 2:54 PM, Martin Batholdy <batholdy@googlemail.com>wrote:> Hi, > > I have a 5 columns x 4 rows matrix and would like to add a diagonal of > zeros so that I end up with a 5x5 matrix. > > x <- matrix(1:20, 4,5) > > > what is the easiest way to accomplish this in R? > > > thanks for any suggestions! > ______________________________________________ > 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. >[[alternative HTML version deleted]]
You could also try:
x1<-matrix(0,5,5)
indx<-which(!is.na(x1),arr.ind=TRUE)
x1[indx[indx[,1]!=indx[,2],]]<- as.vector(x)
#Speed comparison:
set.seed(48)
m1<- matrix(sample(1:40,4500*4499,replace=TRUE),ncol=4500)
m2<- matrix(0,4500,4500)
system.time({
indx<- which(m2==0,arr.ind=TRUE)
m2[indx[indx[,1]!=indx[,2],]]<- as.vector(m1)
})
# user? system elapsed
#? 3.376?? 0.648?? 4.037
m3 <- matrix(0,4500,4500)
system.time({
m3[upper.tri(m3)] <- m1[upper.tri(m1)]
m3[lower.tri(m3)] <- m1[lower.tri(m1, diag=TRUE)]
})
# user? system elapsed
#? 4.236?? 0.460?? 4.709
?identical(m2,m3)
#[1] TRUE
A.K.
----- Original Message -----
From: Martin Batholdy <batholdy at googlemail.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc:
Sent: Saturday, August 3, 2013 2:54 PM
Subject: [R] add diagonal to matrix
Hi,
I have a 5 columns x 4 rows matrix and would like to add a diagonal of zeros so
that I end up with a 5x5 matrix.
x <- matrix(1:20, 4,5)
what is the easiest way to accomplish this in R?
thanks for any suggestions!
______________________________________________
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.
Hi,
I have another method:
set.seed(48)
n <- 4500
m1 <- matrix(sample(1:40,n*(n-1),replace=TRUE),ncol=n)
m2 <- vector("numeric",length=n^2)
system.time({m2[!m2%in%seq.int(n)^2] <-
as.vector(m1);m3<-array(m2,dim=c(n,n))})
# user system elapsed
# 1.43 0.28 1.87
Best Regards!
Fechy
----- Original Message -----
???: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] ??
arun
????: 2013?8?4? 9:10
???: Martin Batholdy
??: R help
??: Re: [R] add diagonal to matrix
You could also try:
x1<-matrix(0,5,5)
indx<-which(!is.na(x1),arr.ind=TRUE)
x1[indx[indx[,1]!=indx[,2],]]<- as.vector(x)
#Speed comparison:
set.seed(48)
m1<- matrix(sample(1:40,4500*4499,replace=TRUE),ncol=4500)
m2<- matrix(0,4500,4500)
system.time({
indx<- which(m2==0,arr.ind=TRUE)
m2[indx[indx[,1]!=indx[,2],]]<- as.vector(m1)
})
# user system elapsed
# 3.376 0.648 4.037
m3 <- matrix(0,4500,4500)
system.time({
m3[upper.tri(m3)] <- m1[upper.tri(m1)]
m3[lower.tri(m3)] <- m1[lower.tri(m1, diag=TRUE)]
})
# user system elapsed
# 4.236 0.460 4.709
identical(m2,m3)
#[1] TRUE
A.K.
----- Original Message -----
From: Martin Batholdy <batholdy at googlemail.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc:
Sent: Saturday, August 3, 2013 2:54 PM
Subject: [R] add diagonal to matrix
Hi,
I have a 5 columns x 4 rows matrix and would like to add a diagonal of zeros so
that I end up with a 5x5 matrix.
x <- matrix(1:20, 4,5)
what is the easiest way to accomplish this in R?
thanks for any suggestions!
______________________________________________
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.
______________________________________________
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.
Hi,
I have another method:
set.seed(48)
n <- 4500
m1 <- matrix(sample(1:40,n*(n-1),replace=TRUE),ncol=n)
m2 <- vector("numeric",length=n^2)
system.time({sqn <- seq.int(n);m2[!seq_along(m2)%in%(sqn+(sqn-1)*n)] <-
as.vector(m1);m3<-array(m2,dim=c(n,n))})
# user system elapsed
# 1.70 0.19 1.92
I'm so sorry for my mistake in former mail, using error expression :
seq_along(m2)%in%n^2. Sorry again for the error and confusion from my email.
Best Regards!
Fechy
----- Original Message -----
???: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] ??
arun
????: 2013?8?4? 9:10
???: Martin Batholdy
??: R help
??: Re: [R] add diagonal to matrix
You could also try:
x1<-matrix(0,5,5)
indx<-which(!is.na(x1),arr.ind=TRUE)
x1[indx[indx[,1]!=indx[,2],]]<- as.vector(x)
#Speed comparison:
set.seed(48)
m1<- matrix(sample(1:40,4500*4499,replace=TRUE),ncol=4500)
m2<- matrix(0,4500,4500)
system.time({
indx<- which(m2==0,arr.ind=TRUE)
m2[indx[indx[,1]!=indx[,2],]]<- as.vector(m1)
})
# user system elapsed
# 3.376 0.648 4.037
m3 <- matrix(0,4500,4500)
system.time({
m3[upper.tri(m3)] <- m1[upper.tri(m1)]
m3[lower.tri(m3)] <- m1[lower.tri(m1, diag=TRUE)]
})
# user system elapsed
# 4.236 0.460 4.709
identical(m2,m3)
#[1] TRUE
A.K.
----- Original Message -----
From: Martin Batholdy <batholdy at googlemail.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc:
Sent: Saturday, August 3, 2013 2:54 PM
Subject: [R] add diagonal to matrix
Hi,
I have a 5 columns x 4 rows matrix and would like to add a diagonal of zeros so
that I end up with a 5x5 matrix.
x <- matrix(1:20, 4,5)
what is the easiest way to accomplish this in R?
thanks for any suggestions!
______________________________________________
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.
______________________________________________
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.