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.
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]
Right, I think I understand the question.
library(magic)
?subsums
If you want a windowed moving average, do:
x - matrix(1:100,10,10)
subsums(x,6,FUN=mean,pad=NA,wrap=F)[6:10,6:10]
If you want block average, do:
subsums(x,2,FUN=mean,pad=NA,wrap=F)[seq(2,10,2),seq(2,10,2)]
which agrees
Assuming the problem is to partition the 10x10 matrix x into 25 two by two
squares and then average each of those squares, try this:
apply(array(x, c(2,5,2,5)), c(2,4), mean)
On 7/27/06, Vladimir Eremeev [EMAIL PROTECTED] wrote:
Dear r-help,
I have a matrix, suppose, 10x10, and I need the
Dear jim,
Yes.
But, unfortunately, two nested for loops will execute very slow.
It is not very serious problem to do my task with an image
processing package, I am wondering if it is efficiently possible with
R.
Thursday, July 27, 2006, 2:20:13 PM, you wrote:
jh Is this what you want: the mean
Dear Robin,
Thank you, seems it is what I need.
---
Best regards,
Vladimirmailto:[EMAIL PROTECTED]
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Dear Sean,
Thursday, July 27, 2006, 3:31:31 PM, you wrote:
SOR Hi Vladimir,
SOR I was wondering whether this was image related :-)
Yes, that's right, I am doing image processing with R.
SOR would one of the image related libraries do it for you?
SOR looking at
SOR
