[R] interpolation function

[Liaw, Andy]

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, Îâ ê» 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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