phyperR {DPQ}

R-only version of R's original phyper() algorithm

Description

An R version of the first phyper() algorithm in R, which was used up to svn rev 30227 on 2004-07-09.

Usage

phyperR(q, m, n, k, lower.tail=TRUE, log.p=FALSE)

Arguments

q

vector of quantiles representing the number of white balls drawn without replacement from an urn which contains both black and white balls.

m

the number of white balls in the urn.

n

the number of black balls in the urn.

k

the number of balls drawn from the urn, hence must be in 0,1,\dots, m+n.

lower.tail

logical; if TRUE (default), probabilities are P[X \le x], otherwise, P[X > x].

log.p

logical; if TRUE, probabilities p are given as log(p).

Value

a numeric vector similar to phyper(q, m, n, k).

Note

The original argument list in C was (x, NR, NB, n) where there were red and black balls in the urn.

Note that we have vectorized a translation to R of the original C code.

Author(s)

Martin Maechler

See Also

phyper and our phyperR2() for the pure R version of the newer (Welinder) phyper() algorithm

Examples

m <- 9:12; n <- 7:10; k <- 10
x <- 0:(k+1) # length 12
## confirmation that recycling + lower.tail, log.p now work:
for(lg in c(FALSE,TRUE))
  for(lt in c(FALSE, TRUE)) {
    cat("(lower.tail = ", lt, " -- log = ", lg,"):\n", sep="")
    withAutoprint({
      (rr <-
           cbind(x, m, n, k, # recycling (to 12 rows)
                 ph  = phyper (x, m, n, k, lower.tail=lt, log.p=lg),
                 phR = phyperR(x, m, n, k, lower.tail=lt, log.p=lg)))
      all.equal(rr[,"ph"], rr[,"phR"], tol = 0)
      ## saw   4.706e-15 1.742e-15 7.002e-12 1.086e-15  [x86_64 Lnx]
      stopifnot(all.equal(rr[,"ph"], rr[,"phR"],
                          tol = if(lg && !lt) 2e-11 else 2e-14))
    })
  }