[R] variable pattern

[Prof Brian D Ripley]

On Mon, 5 Feb 2001, Jan Seidel wrote:

> Suppose I've got p vectors x1, ..., xp each of length n merged in a (n x
> p)-matrix X.
> Now I want to calculate the number of distinct values of row-vectors
> (x_i1, ..., x_ip).
> Is there a way to do this in R? Thanks in advance,

Completely distinct row vectors?  Take a look at the code of
merge.data.frame.  Something like

    bx <- matrix(as.character(a), nrow(a))
    bx <- drop(apply(bx, 1, function(x) paste(x, collapse = "\r")))
    length(unique(bx))

This turns each row into a single character string, and counts the unique
ones.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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