

   sample {base}                                R Documentation

   RRaannddoomm SSaammpplleess aanndd PPeerrmmuuttaattiioonnss

   DDeessccrriippttiioonn::

        `sample' takes a sample of the specified size from the
        elements of `x' using either with or without replace-
        ment.

   UUssaaggee::

        sample(x, size, replace=FALSE, prob)

   AArrgguummeennttss::

          x: Either a (numeric, complex, character or logical)
             vector of more than one elements from which to
             choose, or a positive integer.

       size: A positive integer giving the number of items to
             choose.

    replace: Should sampling be with replacement?

       prob: A vector of probabilities of obtaining the ele-
             ments of the vector being sampled.

   DDeettaaiillss::

        If `x' has length 1, sampling takes place from `1:x'.

        By default `size' is equal to `length(x)' so that `sam-
        ple(x)' generates a random permutation of the elements
        of `x' (or `1:x').

        The optional `prob' argument can be used to give a vec-
        tor of probabilities of obtaining the elements of the
        vector being sampled. If `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.

   EExxaammpplleess::

        x <- 1:12
        # a random permutation
        sample(x)
        # bootstrap sampling
        sample(x,replace=TRUE)

        # 100 Bernoulli trials
        sample(c(0,1), 100, replace = TRUE)

