# Re: [R] pairs matchning

From: <TobiasBr_at_Taquanta.com>
Date: Thu 26 Oct 2006 - 16:12:48 GMT

Hi

You could try to find an equivalent representation as a string and try to match those.

> (A <- cbind(sample(1:2, 10, rep=TRUE), sample(1:2, 10, rep=TRUE)))

[,1] [,2]

``` [1,]    1    2
[2,]    1    2
[3,]    1    2
[4,]    2    2
[5,]    1    1
[6,]    1    2
[7,]    1    2
[8,]    1    1
[9,]    1    2
```

[10,] 1 1
> (B <- unique(A))

[,1] [,2]

```[1,]    1    2
[2,]    2    2
[3,]    1    1
```

> strRep <- function(mat) apply(mat, 1, function(x) paste(x, collapse=";"))
> strRep(B)

[1] "1;2" "2;2" "1;1"
> (idx <- match(strRep(A), strRep(B)))

[1] 1 1 1 2 3 1 1 3 1 3
> B[idx, ]

[,1] [,2]

``` [1,]    1    2
[2,]    1    2
[3,]    1    2
[4,]    2    2
[5,]    1    1
[6,]    1    2
[7,]    1    2
[8,]    1    1
[9,]    1    2
```

[10,] 1 1
>

HTH
>-----Original Message-----
>From: r-help-bounces@stat.math.ethz.ch
>[mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Federico Calboli

>Sent: 26 October 2006 06:48 PM
>To: r-help
>Subject: [R] pairs matchning
>
>Hi All,
>
>I have two numerical matrices of 2 columns and many rows.
>
>The two coulumns of matrix (1) form a number of 'pairs' of
>numbers, e.g:
>
> [,1] [,2]
>[1,] 1 0
>[2,] 3 4
>[3,] 3 4
>[4,] 5 8
>[5,] 1 0
>[6,] 1 0
>[7,] 6 7

>
>Matrix (2) contains the *unique* pairs:
>
> [,1] [,2]
>[1,] 1 0
>[2,] 3 4
>[3,] 5 8
>[4,] 6 7

>
>
>I would like to create a vector matching the pairs in matrix
>(1) to the unique pairs in matrix (2), e.g:
>
>[1] 1 2 2 3 1 1 4

>
>(done by hand)
>
>match() does not seem to be able to handle pairs, and I don't
>seem to be able to find an elegant solution...
>
>Cheers,
>
>Federico
>
>--
>Federico C. F. Calboli
>Department of Epidemiology and Public Health Imperial College,
>St Mary's Campus Norfolk Place, London W2 1PG
>
>Tel +44 (0)20 7594 1602 Fax (+44) 020 7594 3193
>
>f.calboli [.a.t] imperial.ac.uk
>f.calboli [.a.t] gmail.com
>
>______________________________________________
>R-help@stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
>

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