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Re: AI-GEOSTATS: about gstat and the variogram cloud

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  • Edzer J. Pebesma
    Lisa, you are right: gstat uses np to encode the information about which point pairs contribute to a single variogram cloud point.The relation between np and
    Message 1 of 2 , Jan 26, 2004
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      Lisa, you are right: gstat uses np to encode the information
      about which point pairs contribute to a single variogram
      cloud point.The relation between np and the left and
      right field are found in the function print.variogram.cloud:

      function (x, ...)
      {
      x$left = x$np%%2^16 + 1
      x$right = x$np%/%2^16 + 1
      x$np = NULL
      print(data.frame(x), ...)
      }

      Furthermore, I cannot reproduce your problem; in
      S-Plus 6.1r1 for Windows, I get:

      > n=1300
      > x=data.frame(x=runif(n),y=runif(n),z=runif(n),v=rnorm(n))
      > x.vc=variogram(v~1,~x+y+z,x,cloud=T)
      > x.vc[1:10,]
      dist gamma dir.hor dir.ver id left right
      1 0.4339541 0.0044311723 0 0 1 3 2
      2 0.3170554 1.6191470800 0 0 1 4 2
      3 0.2289803 1.7929856870 0 0 1 4 3
      4 0.4712303 3.6202814606 0 0 1 5 1
      5 0.4258145 0.1108600917 0 0 1 5 2
      6 0.5333062 0.8826612122 0 0 1 5 4
      7 0.3405685 3.7223526406 0 0 1 6 1
      8 0.4752595 0.8333212054 0 0 1 6 4
      9 0.4408808 0.0007094885 0 0 1 6 5
      10 0.2938981 1.0232285872 0 0 1 7 3
      >

      Maybe you forgot to load the gstat library before
      your call to print.variogram.cloud?
      --
      Edzer

      lisa pizzol wrote:

      > Dear list members,
      >
      > I’m using GSTAT (in S-Plus) to build a 3D semi-variogram. I have about
      > 1300 samples, I built a directional variogram and I created a related
      > file with the variogram cloud (about 110000 pairs). My problem is that
      > I can not print this file (print.variogram.cloud), the program says
      > that it makes a bad operation and it closes itself; is it because this
      > file is too large? if I go to the Object Editor I can open this file
      > file but I can not see the numbers of the samples that form the pairs
      > (there are not the columns “left” and “right” (for variogram.cloud:
      > data id (row number) of one of the data pair) like I expected).
      > Instead of these columns there is the column called “np” (the number
      > of point pairs for this estimate) that shouldn’t be in this file but
      > only in the variogram file. The column “np” has strange numbers that I
      > can not understand. Can I calculate the data id (row number) of the
      > samples of a pair from the numbers in the “np” column? where did I go
      > wrong?
      >
      > Thank you very much.
      >
      > Best regards,
      >
      > Lisa
      >


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