Greetings Everyone,
I need to do a computation that requires all unique products of two columns
of a matrix (or data frame, I'm not picky), including the multiplication of
the columns with themselves.
That is, for a 2x3 matrix:
test <- matrix(1:6, nrow=2)
I need:
m1<-test[,1]*test[,1]
m2<-test[,1]*test[,2]
m3<-test[,1]*test[,3]
m4<-test[,2]*test[,2]
m5<-test[,2]*test[,3]
m6<-test[,3]*test[,3]
and products such as:
m7<-test[,3]*test[,2]
are redundant.
The problem is that the data sets will dictate the number of columns, and
each data set will likely be different. I need to have the code generate the
correct number of products for the general case.
Because this "all-possible-2-column-products" computation is going to be
done at each iteration, until convergence, I would like the above done
without looping.
I will compile the answers I receive and post them to the group.
Thanks in advance,
Pam
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Pam Goodman
Biometrician
Northwest Indian Fisheries Commission
6730 Martin Way E
Olympia, WA 98516-5540
Phone: (360)438-1181 ext 380
Fax: (360)753-8659
http://www.nwifc.wa.gov/
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