[R] comparing two matrices

From: Adrian Dusa <dusa.adrian_at_gmail.com>
Date: Sat 20 Jan 2007 - 22:14:45 GMT

Dear helpeRs,

I have two matrices:
mat1 <- expand.grid(0:2, 0:2, 0:2)
mat2 <- aa[c(19, 16, 13, 24, 8), ]

where mat2 is always a subset of mat1

I need to find the corersponding row numbers in mat1 for each row in mat2. For this I have the following code:

apply(mat2, 1, function(x) {

    which(apply(mat1, 1, function(y) {

        sum(x == y)
        }) == ncol(mat1))

    })

The code is vectorized, but I wonder if there is a simpler (hence faster) matrix computation that I miss.

Thank you,
Adrian

-- 
Adrian Dusa
Romanian Social Data Archive
1, Schitu Magureanu Bd
050025 Bucharest sector 5
Romania
Tel./Fax: +40 21 3126618 \
          +40 21 3120210 / int.101

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Received on Sun Jan 21 09:22:46 2007

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