[R] Test for column equality across matrices

[arun]

Hi,
One way would be:
 which(apply(t(B),1,paste,collapse="")%in%apply(t(A),1,paste,collapse=""))
#[1] 105 196 274 340 395
B[,105]
#[1]  1 15 16
 B[,196]
#[1]  2 15 16
 B1<-B[,!apply(t(B),1,paste,collapse="")%in%apply(t(A),1,paste,collapse="")]
 dim(B1)
#[1]   3 555
 dim(B)
#[1]   3 560

#or
B2<-B[,is.na(match(interaction(as.data.frame(t(B))),interaction(as.data.frame(t(A)))))]
 identical(B1,B2)
#[1] TRUE


A.K.





----- Original Message -----
From: Thiem Alrik <thiem at sipo.gess.ethz.ch>
To: "mailman, r-help" <r-help at r-project.org>
Cc: 
Sent: Saturday, July 13, 2013 9:45 AM
Subject: [R] Test for column equality across matrices

Dear list,

I have two matrices

A <- matrix(t(expand.grid(c(1,2,3,4,5), 15, 16)), nrow = 3)
B <- combn(16, 3)

Now I would like to exclude all columns from the 560 columns in B which are identical to any 1 of the 6 columns in A. How could I do this?

Many thanks and best wishes,

Alrik

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