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\name{sample}
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\name{sample}
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\alias{sample}
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\title{Random Samples and Permutations}
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\title{Random Samples and Permutations}
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\description{
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  \code{sample} takes a sample of the specified size from the elements
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  of \code{x} using either with or without replacement.
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}
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\usage{
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\usage{
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sample(x, size, replace = FALSE, prob = NULL)
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sample(x, size, replace = FALSE, prob = NULL)
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}
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}
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\alias{sample}
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\arguments{
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\arguments{
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  \item{x}{Either a (numeric, complex, character or logical)
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  \item{x}{Either a (numeric, complex, character or logical) vector of
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    vector of more than one element from which to
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    choose, or a positive integer.}
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    more than one element from which to choose, or a positive integer.}
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  \item{size}{non-negative integer giving the number of items to choose.}
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  \item{size}{non-negative integer giving the number of items to choose.}
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  \item{replace}{Should sampling be with replacement?}
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  \item{replace}{Should sampling be with replacement?}
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  \item{prob}{A vector of probability weights for obtaining the elements
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  \item{prob}{A vector of probability weights for obtaining the elements
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    of the vector being sampled.}
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    of the vector being sampled.}
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}
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}
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\description{
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  \code{sample} takes a sample of the specified size from
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  the elements of \code{x} using either with or without replacement.
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}
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\details{
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\details{
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  If \code{x} has length 1, sampling takes place from
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  If \code{x} has length 1, sampling takes place from
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  \code{1:x}.  \emph{Note} that this convenience feature may lead to
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  \code{1:x}.  \emph{Note} that this convenience feature may lead to
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  undesired behaviour when \code{x} is of varying length
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  undesired behaviour when \code{x} is of varying length
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  \code{sample(x)}.  See the \code{resample()} example below.
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  \code{sample(x)}.  See the \code{resample()} example below.
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sample(x,replace=TRUE)
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sample(x,replace=TRUE)
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# 100 Bernoulli trials
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# 100 Bernoulli trials
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sample(c(0,1), 100, replace = TRUE)
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sample(c(0,1), 100, replace = TRUE)
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## More careful bootstrapping --  Consider this when
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## More careful bootstrapping --  Consider this when using sample()
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## using sample() programmatically (i.e. in your function or simulation)!
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## programmatically (i.e., in your function or simulation)!
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# sample()'s surprise -- example
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# sample()'s surprise -- example
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x <- 1:10
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x <- 1:10
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    sample(x[x >  8]) # length 2
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    sample(x[x >  8]) # length 2
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    sample(x[x >  9]) # oops -- length 10!
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    sample(x[x >  9]) # oops -- length 10!