Re: [S] distributional mode

Prof Brian Ripley (ripley@stats.ox.ac.uk)
Tue, 1 Sep 1998 13:55:12 +0100 (BST)


> From: Mike Richman <richman@trumpkin.gcn.ou.edu>
>
> We know that the Splus command "mode" does not give the statistical
> mode of a distribution. I've been kludging the table command. What
> I'm after (if possible) is a command one can use with "apply" to give
> the statistical mode of the rows/columns of a matrix. Anyone have a
> simple solution?

What is the `statistical mode', presumably of a vector? I know what a
mode of a density is (but not of a distribution: it depends on the base
measure). Unless you have discrete data I think this is meaningless.
IF you do and `mode' means most frequently occurring value:

discmode <- function(x)
{
z <- table(x)
as.numeric(names(z)[z == max(z)])
}

will give all the modes (there could be more than one). To use with apply
you really need to tell us how to get a unique answer (unless you like
interpreting lists, which is what apply will give).

-- 
Brian D. Ripley,                  ripley@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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