Is this what you want: the mean of the surrounding 4 cells?
> x <- matrix(1:100, 10) # create data
> rmean <- matrix(0,5,5) # result matrix
> for (i in 1:5){
+ for (j in 1:5){
+ rmean[i, j] <- mean(x[c(-1,0) + 2 * i, c(-1,0) + 2 * j])
+ }
+ }
> x
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,] 1 11 21 31 41 51 61 71 81 91
[2,] 2 12 22 32 42 52 62 72 82 92
[3,] 3 13 23 33 43 53 63 73 83 93
[4,] 4 14 24 34 44 54 64 74 84 94
[5,] 5 15 25 35 45 55 65 75 85 95
[6,] 6 16 26 36 46 56 66 76 86 96
[7,] 7 17 27 37 47 57 67 77 87 97
[8,] 8 18 28 38 48 58 68 78 88 98
[9,] 9 19 29 39 49 59 69 79 89 99
[10,] 10 20 30 40 50 60 70 80 90 100
> rmean
[,1] [,2] [,3] [,4] [,5]
[1,] 6.5 26.5 46.5 66.5 86.5
[2,] 8.5 28.5 48.5 68.5 88.5
[3,] 10.5 30.5 50.5 70.5 90.5
[4,] 12.5 32.5 52.5 72.5 92.5
[5,] 14.5 34.5 54.5 74.5 94.5
>
On 7/27/06, Vladimir Eremeev <[EMAIL PROTECTED]> wrote:
>
> Dear r-help,
>
> I have a matrix, suppose, 10x10, and I need the matrix 5x5, having
> in each cell a mean value of the cells from the initial matrix.
>
> Please, point me to a function in R, which can help me doing that.
>
> Digging the documentation and mail archives didn't give me a result.
>
> Thank you.
>
> ---
> Best regards,
> Vladimir mailto:[EMAIL PROTECTED]
>
> ______________________________________________
> [email protected] mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
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