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y <- rsample(x,n) or y <- rsample(x,n,T), REAL vector or matrix x,
  positive integer n
y <- rsample(x,n,F) requires n <= nrows(x)

Keywords: random numbers
rsample() is a macro you can use to select a random sample with or
without replacement from the rows of a REAL matrix or vector.

y <- rsample(x, n) and rsample(x, n, T) both select a random sample of
size n from the rows of REAL matrix x.  n is a positive integer.
Sampling is *with* replacement.

y <- rsample(x, n, F) does the same, except that sampling is without
replacement.  It is an error if n > nrows(x).

In both usages, y will be a REAL vector of length n or a REAL n by
ncols(x) matrix.

The following selects a random sample of size 5 drawn without
replacement from {1,2,...,20}:

  Cmd> y <- rsample(run(20),5,F)

  Cmd> y
  (1)          11          10           8           3          18

See also runi(), rnorm().

Gary Oehlert 2003-01-15