\Header{sample}{Random Samples and Permutations}
\keyword{distribution}{sample}
\begin{Description}\relax
\code{sample} takes a sample of the specified size from
the elements of \code{x} using either with or without replacement.\end{Description}
\begin{Usage}
\begin{verbatim}
sample(x, size, replace=FALSE, prob)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] Either a (numeric, complex, character or logical)
vector of more than one elements from which to
choose, or a positive integer.
\item[\code{size}] A positive integer giving the number of items to choose.
\item[\code{replace}] Should sampling be with replacement?
\item[\code{prob}] A vector of probabilities of obtaining the elements
of the vector being sampled.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
If \code{x} has length 1, sampling takes place from
\code{1:x}.

By default \code{size} is equal to \code{length(x)}
so that \code{sample(x)} generates a random permutation
of the elements of \code{x} (or \code{1:x}).

The optional \code{prob} argument can be used to give a vector
of probabilities of obtaining the elements of the vector being
sampled. If \code{replace} is false, these probabilities are applied
sequentially, that is the probability of choosing the next item is
proportional to the probabilities amongst the remaining items.\end{Details}
\begin{Examples}
\begin{ExampleCode}
x <- 1:12
# a random permutation
sample(x)
# bootstrap sampling
sample(x,replace=TRUE)

# 100 Bernoulli trials
sample(c(0,1), 100, replace = TRUE)
\end{ExampleCode}
\end{Examples}

