[R] Binary Matrices

[Huntsinger, Reid]

Actually n^2 doubles. You could insert as.integer() around the call to
round(runif()), to make the matrix have storage mode "integer", but when you
call "eigen" you need a matrix of doubles anyway, so you're not really
saving space. 

If your matrices are large and have mostly zeros, you might benefit from the
SparseM package or the Matrix package.

Reid Huntsinger

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Mark Edmondson-Jones
Sent: Wednesday, April 13, 2005 9:51 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Binary Matrices


I'm wanting to perform analysis (e.g. using eigen()) of binary matrices -
i.e. matrices comprising 0s and 1s.

For example:

n<-1000
test.mat<-matrix(round(runif(n^2)),n,n)
eigen(test.mat,only.values=T)

Is there a more efficient way of setting up test.mat, as each cell only
requires a binary digit?  I imagine R is setting up a structure which could
contain n^2 floats.

Thanks in advance for any help.

Regards,
Mark


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