FAQ
Hello,
I am trying to convert list of pairwise distances to a distance matrix for
spatial analysis (kriging). For instance, I have something like this for
each pair pf points, and I want to convert it to a matrix:

point1 point2 distance
1 1 0
1 2 4
2 2 0
2 1 4

Please let me know if there is a function or method that can do this.

Thanks,
Christy

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  • Daniel Malter at Nov 10, 2008 at 12:27 am
    what should your matrix look like? do you mean something like this?

    p1=c(1,1,2,2)
    p2=c(1,2,1,2)
    d=c(0,4,4,0)

    cbind(p1,p2,d)

    d2=matrix(d,length(d)/2,length(d)/2)
    d2

    Cheers,
    Daniel


    -------------------------
    cuncta stricte discussurus
    -------------------------

    -----Urspr?ngliche Nachricht-----
    Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
    Auftrag von skinny c
    Gesendet: Sunday, November 09, 2008 7:11 PM
    An: r-help at r-project.org
    Betreff: [R] how to convert indvidual pairwise distances to matrix

    Hello,
    I am trying to convert list of pairwise distances to a distance matrix for
    spatial analysis (kriging). For instance, I have something like this for
    each pair pf points, and I want to convert it to a matrix:

    point1 point2 distance
    1 1 0
    1 2 4
    2 2 0
    2 1 4

    Please let me know if there is a function or method that can do this.

    Thanks,
    Christy

    [[alternative HTML version deleted]]

    ______________________________________________
    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.
  • Jorge Ivan Velez at Nov 10, 2008 at 12:29 am
    Dear Christy,
    Take a look at

    http://www.nabble.com/Efficient-way-to-fill-a-matrix-to20351720.html#a20351720


    Here are three options to do what you want:

    # Data set
    mydata=read.table(textConnection("
    point1 point2 distance
    1 1 0
    1 2 4
    2 2 0
    2 1 4"),header=TRUE)
    closeAllConnections()

    # Option 1
    with(mydata,tapply(distance,list(point1,point2),"[[",1))

    # Option 2
    M <- matrix(,2,2)
    attach(mydata)
    M[cbind(point1,point2)]<-distance

    # Option 3
    library(reshape)
    cast(mydata, point1~point2)


    HTH,

    Jorge


    On Sun, Nov 9, 2008 at 7:11 PM, skinny c wrote:

    Hello,
    I am trying to convert list of pairwise distances to a distance matrix for
    spatial analysis (kriging). For instance, I have something like this for
    each pair pf points, and I want to convert it to a matrix:

    point1 point2 distance
    1 1 0
    1 2 4
    2 2 0
    2 1 4

    Please let me know if there is a function or method that can do this.

    Thanks,
    Christy

    [[alternative HTML version deleted]]

    ______________________________________________
    r-help@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.

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