The R Project SVN R-packages

\name{boot.array}
\alias{boot.array}
\title{
Bootstrap Resampling Arrays
}
\description{
  This function takes a bootstrap object calculated by one of the
  functions \code{boot}, \code{censboot}, or \code{tilt.boot} and
  returns the frequency (or index) array for the bootstrap
  resamples.
}
\usage{
boot.array(boot.out, indices)
}
\arguments{
\item{boot.out}{
  An object of class \code{"boot"} returned by one of the generation
  functions for such an object.
}
\item{indices}{
  A logical argument which specifies whether to return the frequency
  array or the raw index array.  The default is \code{indices=FALSE}
  unless \code{boot.out} was created by \code{tsboot} in which case the
  default is \code{indices=TRUE}.
}}
\value{
  A matrix with \code{boot.out$R} rows and \code{n} columns where
  \code{n} is the number of observations in \code{boot.out$data}.  If
  \code{indices} is \code{FALSE} then this will give the frequency of
  each of the original observations in each bootstrap resample. If
  \code{indices} is \code{TRUE} it will give the indices of the
  bootstrap resamples in the order in which they would have been passed
  to the statistic.
}
\section{Side Effects}{
  This function temporarily resets \code{.Random.seed} to the value in
  \code{boot.out$seed} and then returns it to its original value at the
  end of the function.
}
\details{
  The process by which the original index array was generated is
  repeated with the same value of \code{.Random.seed}.  If the frequency
  array is required then \code{freq.array} is called to convert the
  index array to a frequency array.
  
  A resampling array can only be returned when such a concept makes
  sense.  In particular it cannot be found for any parametric or
  model-based resampling schemes.  Hence for objects generated by
  \code{censboot} the only resampling scheme for which such an array can
  be found is ordinary case resampling. Similarly if \code{boot.out$sim}
  is \code{"parametric"} in the case of \code{boot} or \code{"model"} in
  the case of \code{tsboot} the array cannot be found.  Note also that
  for post-blackened bootstraps from \code{tsboot} the indices found
  will relate to those prior to any post-blackening and so will not be
  useful.

  Frequency arrays are used in many post-bootstrap calculations such as
  the jackknife-after-bootstrap and finding importance sampling weights.
  They are also used to find empirical influence values through the
  regression method.
}
\seealso{
  \code{\link{boot}}, \code{\link{censboot}}, \code{\link{freq.array}},
  \code{\link{tilt.boot}}, \code{\link{tsboot}}
}
\examples{
#  A frequency array for a nonparametric bootstrap
city.boot <- boot(city, corr, R = 40, stype = "w")
boot.array(city.boot)

perm.cor <- function(d,i) cor(d$x,d$u[i])
city.perm <- boot(city, perm.cor, R = 40, sim = "permutation")
boot.array(city.perm, indices = TRUE)
}
\keyword{nonparametric}
% Converted by Sd2Rd version 1.15.