[R] efficiently replacing values in a matrix

Matthew Keller mckellercran at gmail.com
Wed Apr 16 21:52:22 CEST 2008

Hello all,

I should probably know this by now... Anyway:

I have a large matrix (dim(data) is 3000  18000). In each element are
one of the following character strings "0/0", "1/1", "1/2", "2/2". I
wanted to replace "0/0" with NA and the other three with 0,1,2
respectively. To accomplish just the first of these four steps I did

data[data=="0/0"] <- NA

Which is still running after 13 hours. I have 18 GB RAM and running 64
bit R. What is a more efficient way to accomplish this (I've already
done it using sed in UNIX - but want to know how to do so in R)?
Thanks in advance,


Matthew C Keller
Asst. Professor of Psychology
University of Colorado at Boulder

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