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\name{getarrvec}
\alias{getarrvec}
\title{Compute and return weaving permutation for conversion from wst objects to wd class objects. }
\description{
Computes weaving permutation for conversion from \code{\link{wst}} objects to \code{\link{wd}}
}
\usage{
getarrvec(nlevels, sort=TRUE)
}
\arguments{
\item{nlevels}{The \code{number of levels} in the non-decimated transform for which the permutation is to be computed.}
\item{sort}{If \code{TRUE} then compute permutation for indexing a \code{\link{wst}} object. If \code{FALSE} then compute permutation for indexing a \code{wd} object.}
}
\details{
Conversion of \code{\link{wst}} objects into \code{\link{wd}} objects and vice versa can be carried out using the \code{\link{convert.wst}} and \code{\link{convert.wd}} functions. These latter functions depend on this getarrvec function to compute the permutation which maps coefficients from one ordering to the other.
This function returns a matrix which gives the necessary permutations for scale levels 1 to \code{nlevels-1}. If you want to get the permutation for the level 0 coefficients of the \code{\link{wst}} object you will have to call the \code{\link{levarr}} function directly.
This permutation is described in Nason, Sapatinas and Sawczenko, 1998.
The function that actually computes the permutations is \code{\link{levarr}}. This function just combines the results from \code{\link{levarr}}.
}
\value{
A matrix with \code{nlevel}s-1 columns. Column 1 corresponds to scale level \code{nlevels-1} in the \code{\link{wst}} object, and column \code{nlevels-1} corresponds to scale level 1 in the \code{\link{wst}} object. Replace \code{\link{wst}} by \code{\link{wd}} if \code{sort=FALSE}.
}
\section{RELEASE}{Version 3.6 Copyright Guy Nason 1997 }
\seealso{
\code{\link{convert}}, \code{\link{convert.wd}}, \code{\link{convert.wst}}, \code{\link{levarr}}, \code{\link{wst}}, \code{\link{wst.object}}, \code{\link{wpst}}.
}
\examples{
#
# What would the permutation be for a wst
# object with 4 levels?
#
arrvec <- getarrvec(4)
#arrvec
# [,1] [,2] [,3]
# [1,] 1 1 1
# [2,] 9 9 9
# [3,] 2 5 5
# [4,] 10 13 13
# [5,] 3 2 3
# [6,] 11 10 11
# [7,] 4 6 7
# [8,] 12 14 15
# [9,] 5 3 2
#[10,] 13 11 10
#[11,] 6 7 6
#[12,] 14 15 14
#[13,] 7 4 4
#[14,] 15 12 12
#[15,] 8 8 8
#[16,] 16 16 16
#
# The permutation for level 3 is in column 1
# The permutation for level 2 is in column 2
# The permutation for level 1 is in column 3.
#
# The following shows that the above is the right permutation (for level 2
# at least.
#
# Start off with some random normal data!
#
myrand <- rnorm(1:16)
#
# Now take both the time ordered non-decimated wavelet
# transform and the packet ordered non-decimated wavelet
# transform.
#
myrwdS <- wd(myrand, type="station")
myrwst <- wst(myrand)
#
# Let's look at the level 2 coefficients of myrwdS
#
accessD(myrwdS, level=2)
# [1] -0.73280829 -0.97892279 1.33305777 1.46320165 -0.94790098
# [6] -1.39276215 0.40023757 0.82517249 -0.56317955 -0.89408713
#[11] 0.77166463 1.56204870 -0.34342230 -1.64133182 0.08235115
#[16] 1.05668106
#
# Let's look at the level 2 coefficients of myrwst
#
accessD(myrwst, level=2)
# [1] -0.73280829 -0.94790098 -0.56317955 -0.34342230 1.33305777
# [6] 0.40023757 0.77166463 0.08235115 -0.97892279 -1.39276215
#[11] -0.89408713 -1.64133182 1.46320165 0.82517249 1.56204870
#[16] 1.05668106
#
# O.k. So the coefficients are the same, but they are not in the
# same order as in myrwdS. So let's use the permutation in the
# second column of arrvec to reorder the myrwst coefficients
# to have the same order as the myrwdS ones
#
accessD(myrwst, level=2)[arrvec[,2]]
# [1] -0.73280829 -0.97892279 1.33305777 1.46320165 -0.94790098
# [6] -1.39276215 0.40023757 0.82517249 -0.56317955 -0.89408713
#[11] 0.77166463 1.56204870 -0.34342230 -1.64133182 0.08235115
#[16] 1.05668106
#
# These coefficients have the correct ordering.
}
\keyword{array}
\author{G P Nason}
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