Hi there, I have a matrix similar as: M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE) I hope to get the border subscript of the block with value 1. In the above example, I hope to get: (3,1), (5,1), (5,2), (4,2), (4,3), (1,3), (1,2), (3,2) Is there any function can do that? or any implement idea? Thanks! Best, Jinsong
M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE)
ix <- expand.grid( r = seq.int( nrow( M ) )
, c = seq.int( ncol( M ) )
)
ix[ 1 == c(M), ]
On June 10, 2020 5:29:10 PM PDT, Jinsong Zhao <jszhao at yeah.net>
wrote:>Hi there,
>
>I have a matrix similar as:
>
>M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE)
>
>I hope to get the border subscript of the block with value 1. In the
>above example, I hope to get:
>
>(3,1), (5,1), (5,2), (4,2), (4,3), (1,3), (1,2), (3,2)
>
>Is there any function can do that? or any implement idea? Thanks!
>
>Best,
>Jinsong
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>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.
--
Sent from my phone. Please excuse my brevity.
On 2020-06-10 18:01 -0700, Jeff Newmiller wrote:> On June 10, 2020 5:29:10 PM PDT, Jinsong Zhao wrote: > > > > (3,1), (5,1), (5,2), (4,2), (4,3), (1,3), (1,2), (3,2) > > M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE) > ix <- expand.grid( r = seq.int( nrow( M ) ) > , c = seq.int( ncol( M ) ) > ) > ix[ 1 == c(M), ]Dear Jinsong and Jeff, I thought out this, really similar to Jeff's answer: M <- matrix(c(2, 2, rep(1, 12), 2), nrow=5, byrow=FALSE) points <- expand.grid(1:nrow(M), 1:ncol(M)) points <- apply(points, 1, paste, collapse=",") points <- matrix(paste0("(", points, ")"), nrow=nrow(M)) paste(points[M==1], collapse=", ") you get [1] "(3,1), (4,1), (5,1), (1,2), (2,2), (3,2), (4,2), (5,2), (1,3), (2,3), (3,3), (4,3)" Best, Rasmus -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20200611/5675bb5e/attachment.sig>
For that, it is more straightforward to use which(M==1, arr.ind=TRUE) However, the desired output has 8 indices, not 12. I don't see what the desired pattern is... - pd> On 11 Jun 2020, at 03:01 , Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote: > > M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE) > ix <- expand.grid( r = seq.int( nrow( M ) ) > , c = seq.int( ncol( M ) ) > ) > ix[ 1 == c(M), ] > > > On June 10, 2020 5:29:10 PM PDT, Jinsong Zhao <jszhao at yeah.net> wrote: >> Hi there, >> >> I have a matrix similar as: >> >> M <- matrix(c(2,2,rep(1,12), 2), nrow = 5,byrow = FALSE) >> >> I hope to get the border subscript of the block with value 1. In the >> above example, I hope to get: >> >> (3,1), (5,1), (5,2), (4,2), (4,3), (1,3), (1,2), (3,2) >> >> Is there any function can do that? or any implement idea? Thanks! >> >> Best, >> Jinsong >> >> ______________________________________________ >> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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. > > -- > Sent from my phone. Please excuse my brevity. > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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.-- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com