[R] A vectorization question

From: Christos Hatzis <christos_at_nuverabio.com>
Date: Tue 09 Jan 2007 - 21:10:39 GMT


Hi,  

A function calculates the absolute difference between the two largest values of each row of a matrix, as shown in the following example code:  

cx <- matrix(runif(15),5)
cy <- t( apply(cx, 1, order, decreasing=TRUE) )  

cz <- rep(0, nrow(cx))
for( i in 1:nrow(cx) ) cz[i] <- abs(diff(cx[i, cy[i,1:2]]))  

Anybody has any ideas on how the last loop can be vectorized?

Thanks.  

Christos Hatzis, Ph.D.
Nuvera Biosciences, Inc.
400 West Cummings Park
Suite 5350
Woburn, MA 01801
Tel: 781-938-3830
www.nuverabio.com <http://www.nuverabio.com/>



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