Hello all, I am trying to sort rows of one matrix by rows of another. Given a1 and a2: ------> a1[,1] [,2] [,3] [1,] 7 6 8 [2,] 4 2 4 [3,] 4 7 2 [4,] 0 3 8 a1 <- structure(c(7, 4, 4, 0, 6, 2, 7, 3, 8, 4, 2, 8), .Dim = c(4L, 3L))> a2[,1] [,2] [,3] [1,] 101 102 103 [2,] 101 102 103 [3,] 101 102 103 [4,] 101 102 103 a2 <- structure(c(101L, 101L, 101L, 101L, 102L, 102L, 102L, 102L, 103L, 103L, 103L, 103L), .Dim = c(4L, 3L)) ------ I want to get a3:> a3[,1] [,2] [,3] [1,] 102 101 103 [2,] 102 101 103 [3,] 103 101 102 [4,] 101 102 103 where the rows of a3 are the rows of a2 sorted according to the rows of a1. I can get the necessary sorting index:> apply(a1, 1, order)[,1] [,2] [,3] [,4] [1,] 2 2 3 1 [2,] 1 1 1 2 [3,] 3 3 2 3 and I can get the rows of a1 sorted according to the rows of a1:> t(apply(a1, 1, function(x) x[order(x)]))[,1] [,2] [,3] [1,] 6 7 8 [2,] 2 4 4 [3,] 2 4 7 [4,] 0 3 8 but I can't get the rows of a2 sorted according to the rows of a1... Thanks, Tim
Johnson, Eric A. (Seattle)
2008-Jul-31 22:05 UTC
[R] sort rows of matrix by rows of another matrix
If you're not adverse to cbind-ing a1 and a2, you can use this: a1a2 <- cbind(a1, a2) a3 <- t(apply(a1a2, 1, function(x) x[order(x[1:ncol(a1)])+ncol(a1)])) Eric -----Original Message----- From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Timothy W. Hilton Sent: Thursday, July 31, 2008 2:19 PM To: r-help at r-project.org Subject: [R] sort rows of matrix by rows of another matrix Hello all, I am trying to sort rows of one matrix by rows of another. Given a1 and a2: ------> a1[,1] [,2] [,3] [1,] 7 6 8 [2,] 4 2 4 [3,] 4 7 2 [4,] 0 3 8 a1 <- structure(c(7, 4, 4, 0, 6, 2, 7, 3, 8, 4, 2, 8), .Dim = c(4L, 3L))> a2[,1] [,2] [,3] [1,] 101 102 103 [2,] 101 102 103 [3,] 101 102 103 [4,] 101 102 103 a2 <- structure(c(101L, 101L, 101L, 101L, 102L, 102L, 102L, 102L, 103L, 103L, 103L, 103L), .Dim = c(4L, 3L)) ------ I want to get a3:> a3[,1] [,2] [,3] [1,] 102 101 103 [2,] 102 101 103 [3,] 103 101 102 [4,] 101 102 103 where the rows of a3 are the rows of a2 sorted according to the rows of a1. I can get the necessary sorting index:> apply(a1, 1, order)[,1] [,2] [,3] [,4] [1,] 2 2 3 1 [2,] 1 1 1 2 [3,] 3 3 2 3 and I can get the rows of a1 sorted according to the rows of a1:> t(apply(a1, 1, function(x) x[order(x)]))[,1] [,2] [,3] [1,] 6 7 8 [2,] 2 4 4 [3,] 2 4 7 [4,] 0 3 8 but I can't get the rows of a2 sorted according to the rows of a1... Thanks, Tim ______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
markleeds at verizon.net
2008-Jul-31 22:34 UTC
[R] sort rows of matrix by rows of another matrix
below is another way ( maybe the same ? )but with an extra line to make
roworder. i'm also not clear on why I have to take the transpose of
the result that
comes back form the apply call. in ?apply, it says that the function
tries to convert the result back to a matrix. that's fine but why does
it do
it in the opposite way from the way the data in sent in ( i.e : by row
). if someone could explain that, i'd appreciate it.
a1 <- structure(c(7, 4, 4, 0, 6, 2, 7, 3, 8, 4, 2, 8), .Dim = c(4L, 3L))
a2 <- structure(c(101L, 101L, 101L, 101L, 102L, 102L, 102L, 102L, 103L,
103L, 103L, 103L), .Dim = c(4L, 3L))
roworder <- t(apply(a1,1,order))
a3 <- t(sapply(1:nrow(a2),function(.rowind) {
a2[.rowind,roworder[.rowind,]]
}))
print(a3)
On Thu, Jul 31, 2008 at 6:05 PM, Johnson, Eric A. (Seattle) wrote:
> If you're not adverse to cbind-ing a1 and a2, you can use this:
>
> a1a2 <- cbind(a1, a2)
>
> a3 <- t(apply(a1a2, 1, function(x) x[order(x[1:ncol(a1)])+ncol(a1)]))
>
> Eric
>
>
> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org]
> On Behalf Of Timothy W. Hilton
> Sent: Thursday, July 31, 2008 2:19 PM
> To: r-help at r-project.org
> Subject: [R] sort rows of matrix by rows of another matrix
>
> Hello all,
>
> I am trying to sort rows of one matrix by rows of another. Given a1
> and
> a2:
>
> ------
>> a1
> [,1] [,2] [,3]
> [1,] 7 6 8
> [2,] 4 2 4
> [3,] 4 7 2
> [4,] 0 3 8
>
> a1 <-
> structure(c(7, 4, 4, 0, 6, 2, 7, 3, 8, 4, 2, 8), .Dim = c(4L, 3L))
>
>> a2
> [,1] [,2] [,3]
> [1,] 101 102 103
> [2,] 101 102 103
> [3,] 101 102 103
> [4,] 101 102 103
>
> a2 <-
> structure(c(101L, 101L, 101L, 101L, 102L, 102L, 102L, 102L, 103L,
> 103L, 103L, 103L), .Dim = c(4L, 3L))
> ------
>
> I want to get a3:
>
>> a3
> [,1] [,2] [,3]
> [1,] 102 101 103
> [2,] 102 101 103
> [3,] 103 101 102
> [4,] 101 102 103
>
> where the rows of a3 are the rows of a2 sorted according to the rows
> of
> a1.
>
> I can get the necessary sorting index:
>> apply(a1, 1, order)
> [,1] [,2] [,3] [,4]
> [1,] 2 2 3 1
> [2,] 1 1 1 2
> [3,] 3 3 2 3
>
> and I can get the rows of a1 sorted according to the rows of a1:
>> t(apply(a1, 1, function(x) x[order(x)]))
> [,1] [,2] [,3]
> [1,] 6 7 8
> [2,] 2 4 4
> [3,] 2 4 7
> [4,] 0 3 8
>
> but I can't get the rows of a2 sorted according to the rows of a1...
>
> Thanks,
> Tim
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.