[R] combination of columns in a matrix

[arun]

Hi,
sapply(colnames(m)[-ncol(m)],function(i) {x1<-cbind(m[,i],m[,ncol(m)]); length(which(x1[,1]!=0 & x1[,2]!=0))})
#A B C 
#2 1 2 
A.K.



----- Original Message -----
From: Hermann Norpois <hnorpois at gmail.com>
To: r-help <r-help at r-project.org>
Cc: 
Sent: Friday, June 14, 2013 3:51 PM
Subject: [R] combination of columns in a matrix

Hello,

I have a matrix m and I want to know how often does 1 (or !0) simultanously
appear in A and REF, B and REF, C and REF.

So actually I wish to automate following expression:
> length (which (m[,1]!=0&m[,4]!=0))
[1] 2
> length (which (m[,2]!=0&m[,4]!=0))
[1] 1



Thanks
Hermann

> m
   A B C REF
r1 1 0 0   1
r2 1 1 0   0
r3 0 0 1   1
r4 0 0 1   1
r5 1 1 0   1
> dput (m)
structure(c(1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0,
1, 1, 1), .Dim = c(5L, 4L), .Dimnames = list(c("r1", "r2", "r3",
"r4", "r5"), c("A", "B", "C", "REF")))

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