[R] triangular matrices input/output
Hi, Is there any package that deals with triangular matrices? Say ways of inputting an upper (lower) triangular matrix? Or convert a vector of length 6 to an upper (lower) triangular matrix (by row/column)? Thanks! - ## PhD candidate in Statistics Big R Fan Big LEGO Fan Big sTaTs Fan ## -- View this message in context: http://r.789695.n4.nabble.com/triangular-matrices-input-output-tp4630310.html Sent from the R help mailing list archive at Nabble.com. __ 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.
Re: [R] triangular matrices input/output
The Matrix package provides good support for many special sorts of
matrices, but here it looks like you probably don't need that
additional machinery for such small case:
makeUpper - function(vec, diag = FALSE){
n - (-1 + sqrt(1 + 8*length(vec)))/2
stopifnot(isTRUE(all.equal(n, as.integer(n
if(!diag) n - n + 1
mat - matrix(0, ncol = n, nrow = n)
mat[upper.tri(mat, diag)] - vec
mat
}
I think does what you want and it's not too hard to generalize to
lower triangular.
E.g.,
v - 1:6
makeUpper(v)
makeUpper(v, diag = TRUE)
It's not super well tested though so caveat lector.
Michael
On Wed, May 16, 2012 at 5:09 PM, casperyc caspe...@hotmail.co.uk wrote:
Hi,
Is there any package that deals with triangular matrices?
Say ways of inputting an upper (lower) triangular matrix?
Or convert a vector of length 6 to an upper (lower) triangular matrix (by
row/column)?
Thanks!
-
##
PhD candidate in Statistics
Big R Fan
Big LEGO Fan
Big sTaTs Fan
##
--
View this message in context:
http://r.789695.n4.nabble.com/triangular-matrices-input-output-tp4630310.html
Sent from the R help mailing list archive at Nabble.com.
__
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.
__
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
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Re: [R] triangular matrices input/output
Do leave the posts for anyone else who might google the same question. (I don't
think you really could delete the post anyways, perhaps only on one mirror)
You could probably use some combination or rev() and t() to fill by row, but I
haven't thought through the geometry all the way yet.
Michael
On May 16, 2012, at 8:13 PM, YUProf caspe...@hotmail.co.uk wrote:
Hi Michael,
I have figured out a 'super' easy way myself and already deleted the post.
It can be done using: (no package necssary)
d=c(3,6,2,1,4,5)
x=matrix(,3,3)
# by column,
x[!lower.tri(x)]=d
I am still trying very hard to think of a way to fit it by row as I sometimes
have to!
THANKS!
Chen
==
Mr Chen YU
PhD candidate in Statistics
School of Mathematics, Statistics and Actuarial Science, University of Kent
D7/D Woolf College, The Pavilion, Giles Lane, Canterbury, Kent CT2 7BQ
Mobile: +44(0)7725003559
==
From: michael.weyla...@gmail.com
Date: Wed, 16 May 2012 19:41:36 -0400
Subject: Re: [R] triangular matrices input/output
To: caspe...@hotmail.co.uk
CC: r-help@r-project.org
The Matrix package provides good support for many special sorts of
matrices, but here it looks like you probably don't need that
additional machinery for such small case:
makeUpper - function(vec, diag = FALSE){
n - (-1 + sqrt(1 + 8*length(vec)))/2
stopifnot(isTRUE(all.equal(n, as.integer(n
if(!diag) n - n + 1
mat - matrix(0, ncol = n, nrow = n)
mat[upper.tri(mat, diag)] - vec
mat
}
I think does what you want and it's not too hard to generalize to
lower triangular.
E.g.,
v - 1:6
makeUpper(v)
makeUpper(v, diag = TRUE)
It's not super well tested though so caveat lector.
Michael
On Wed, May 16, 2012 at 5:09 PM, casperyc caspe...@hotmail.co.uk wrote:
Hi,
Is there any package that deals with triangular matrices?
Say ways of inputting an upper (lower) triangular matrix?
Or convert a vector of length 6 to an upper (lower) triangular matrix (by
row/column)?
Thanks!
-
##
PhD candidate in Statistics
Big R Fan
Big LEGO Fan
Big sTaTs Fan
##
--
View this message in context:
http://r.789695.n4.nabble.com/triangular-matrices-input-output-tp4630310.html
Sent from the R help mailing list archive at Nabble.com.
__
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]]
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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Re: [R] triangular matrices input/output
Hello,
I needed this once.
upper.diag - function(x, byrow=FALSE){
m - sqrt(1 + 8*length(x))
if(abs(m - floor(m)) .Machine$double.eps^0.5)
m - (m - 1)/2
else{
warning(length of 'x' is not a triangular number.)
m - floor((m - 1)/2)
}
y - matrix(0, nrow=m, ncol=m)
if(byrow){
y[lower.tri(y, TRUE)] - x
y - t(y)
}else
y[upper.tri(y, TRUE)] - x
y
}
lower.diag - function(x, byrow=FALSE){
m - sqrt(1 + 8*length(x))
if(abs(m - floor(m)) .Machine$double.eps^0.5)
m - (m - 1)/2
else{
warning(length of 'x' is not a triangular number.)
m - floor((m - 1)/2)
}
y - matrix(0, nrow=m, ncol=m)
if(byrow){
y[upper.tri(y, TRUE)] - x
y - t(y)
}else
y[lower.tri(y, TRUE)] - x
y
}
lower.diag(1:6)
lower.diag(1:10, TRUE)
lower.diag(1:8)
upper.diag(1:6)
upper.diag(1:10, TRUE)
upper.diag(1:12)
Hope this helps,
Rui Barradas
casperyc wrote
Hi,
Is there any package that deals with triangular matrices?
Say ways of inputting an upper (lower) triangular matrix?
Or convert a vector of length 6 to an upper (lower) triangular matrix (by
row/column)?
Thanks!
-
##
PhD candidate in Statistics
Big R Fan
Big LEGO Fan
Big sTaTs Fan
##
--
View this message in context:
http://r.789695.n4.nabble.com/triangular-matrices-input-output-tp4630310.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@ 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.
--
View this message in context:
http://r.789695.n4.nabble.com/triangular-matrices-input-output-tp4630322p4630328.html
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__
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and provide commented, minimal, self-contained, reproducible code.
