## File: combn.Rd

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r-cran-combinat 0.0-8-7
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 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667 \name{combn} \alias{combn} \alias{combn2} \alias{nCm} \title{ Generate all combinations of the elements of x taken m at a time. } \description{ Generate all combinations of the elements of x taken m at a time. If x is a positive integer, returns all combinations of the elements of seq(x) taken m at a time. If argument "fun" is not null, applies a function given by the argument to each point. If simplify is FALSE, returns a list; else returns a vector or an array. "..." are passed unchanged to function given by argument fun, if any. combn2:Generate all combinations of the elements of x taken two at a time. If x is missing, generate all combinations of 1:n taken two at a time (that is, the indices of x that would give all combinations of the elements of x if x with length n had been given). Exactly one of arguments "x" and "n" should be given; no provisions for function evaluation. nCm: Compute the binomial coefficient ("n choose m"), where n is any real number and m is any integer. Arguments n and m may be vectors; they will be replicated as necessary to have the same length. Argument tol controls rounding of results to integers. If the difference between a value and its nearest integer is less than tol, the value returned will be rounded to its nearest integer. To turn off rounding, use tol = 0. Values of tol greater than the default should be used only with great caution, unless you are certain only integer values should be returned. } \usage{ combn(x, m, fun=NULL, simplify=TRUE, ...) } %- maybe also usage' for other objects documented here. \arguments{ \item{x}{ vector source for combinations } \item{m}{ number of elements } \item{fun}{ function to be applied to each combination (may be null) } \item{simplify}{ logical, if FALSE, returns a list, otherwise returns vector or array } \item{\dots}{ args to fun } } \details{ Nijenhuis, A. and Wilf, H.S. (1978) Combinatorial Algorithms for Computers and Calculators. NY: Academic Press. } \value{ see simplify argument } \references{ ~put references to the literature/web site here ~ } \author{ Code by Scott Chasalow, R package and doc prep by Vince Carey, stvjc@channing.harvard.edu} \examples{ combn(letters[1:4], 2) combn(10, 5, min) # minimum value in each combination # Different way of encoding points: combn(c(1,1,1,1,2,2,2,3,3,4), 3, tabulate, nbins = 4) #Compute support points and (scaled) probabilities for a #Multivariate-Hypergeometric(n = 3, N = c(4,3,2,1)) p.f.: # table.mat(t(combn(c(1,1,1,1,2,2,2,3,3,4), 3, tabulate,nbins=4))) } %\keyword{ combinatorics } \keyword{ models } `