Re: [R] interpolation function

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Sat 06 Aug 2005 - 01:26:46 EST


I don't know if what Hao wanted to do is to hang himself, but if so, perhaps here is one possible rope:

> idx <- which(m > 0, arr.ind=TRUE)
> m.nz <- m[idx]
> library(akima)
> (m.int <- interp.new(idx[,1], idx[,2], m.nz, xo=1:9, yo=1:9, extrap=TRUE))
$x
[1] 1 2 3 4 5 6 7 8 9

$y
[1] 1 2 3 4 5 6 7 8 9

$z

              [,1] [,2] [,3] [,4] [,5] [,6] [,7]
 [1,] 57.1356740 55.18522 38.413800 18.086957 2.300000 0.737908 22. 544616
 [2,] 18.8241001 19.35348 3.100000 -20.355403 -41.610566 -51.308028 -40. 090327
 [3,] 3.2234619 8.63630 -5.312670 -29.221287 -53.732091 -69.487619 -67. 130408
 [4,] 1.1000000 13.75521 4.290890 -17.935507 -43.566514 -63.244671 -67. 612515
 [5,] 3.2013295 25.25298 22.408739 4.000000 -20.615776 -42.081126 -51. 038588
 [6,] 0.2005624 33.62766 39.538938 27.083292 5.618185 -15.498922 -26. 910566
 [7,] -17.2478151 29.37731 46.179546 41.812431 25.633428 7.000000 -4. 730390
 [8,] -58.4893169 3.00000 32.828625 38.685475 29.928013 15.913700 6. 000000
 [9,] -130.5161684 -53.43667 -9.550716 8.258617 9.000000 1.817369 -3. 604296

             [,8] [,9]

 [1,]  76.7287988 170.407375
 [2,]   1.4000000  80.913745
 [3,] -37.3029968  28.876027
 [4,] -47.3125835   6.953079
 [5,] -38.1307000   6.000000
 [6,] -19.2592860  16.750369
 [7,]  -0.2080329  29.451691
 [8,]   9.3350825  34.229953
 [9,]   0.8303142  21.211142

Note how wild the interpolated/extrapolated values can be...

Andy

> From: Adaikalavan Ramasamy
>
> I do not understand your question. If this was not a sparse
> matrix, then
> I would have asked you refer into the missing value literature. Even
> there, people generally remove any columns/rows that have too many
> missing values to avoid unreliable results.
>
> And since this is a sparse matrix, you are going to have too many
> missing values on all rows and columns. I could be wrong but if I am,
> someone will tell me that soon enough.
>
> Regards, Adai
>
>
>
> On Fri, 2005-08-05 at 12:12 +0000, wrote:
> > Hi,
> > I have a sparse matrix.I want to fill values into the
> entries whose value
> > is 0.The new generated values should come from the
> interpolation of the
> > values have existed.Does R provide such interpolation
> functions which
> > operate on Matrix, for example ,such a matrix below
> > 0 0 0 0 2.3 0 0 0 0
> > 0 0 3.1 0 0 0 0 1.4 0
> > 0 0 0 0 0 0 0 0 0
> > 1.1 0 0 0 0 0 0 0 0
> > 0 0 0 4 0 0 0 0 6
> > 0 0 0 0 0 0 0 0 0
> > 0 0 0 0 0 7 0 0 0
> > 0 3 0 0 0 0 6 0 0
> > 0 0 0 0 9 0 0 0 0
> > thanks a lot
> > hao wu
> >
> > ______________________________________________
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Aug 06 01:32:31 2005

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