[R] Geometric mean of rows in matrix

[David Winsemius]

On Aug 20, 2009, at 2:22 PM, Edward Chen wrote:

> Is there a function or an easier way to computer geometric means of  
> each
> rows in a nxn matrix and spit out in an 1xn matrix ?

 > xx <- matrix(10+rnorm(100), 10)

 > apply(xx, 1, function(x) exp(mean(log(x))) )
  [1] 10.084711 10.034054  9.622909  9.780703 10.085467  9.800346  
10.283556  9.666453  9.802996
[10]  9.917821

This of course will return NaN if there are any negative values. There  
are also several implementations of geometric mean functions that can  
be found with the obvious search strategy at:

http://search.r-project.org/nmz.html

-- 
David Winsemius, MD
Heritage Laboratories
West Hartford, CT