Re: [R] how to resample (or resize) matrix?
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 8191
[2,]2 12 22 32 42 52 62 72 8292
[3,]3 13 23 33 43 53 63 73 8393
[4,]4 14 24 34 44 54 64 74 8494
[5,]5 15 25 35 45 55 65 75 8595
[6,]6 16 26 36 46 56 66 76 8696
[7,]7 17 27 37 47 57 67 77 8797
[8,]8 18 28 38 48 58 68 78 8898
[9,]9 19 29 39 49 59 69 79 8999
[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,
Vladimirmailto:[EMAIL PROTECTED]
__
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
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?
[[alternative HTML version deleted]]
__
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
and provide commented, minimal, self-contained, reproducible code.
Re: [R] how to resample (or resize) matrix?
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 with Jim's solution below.
HTH
rksh
On 27 Jul 2006, at 11:20, jim holtman wrote:
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 8191
[2,]2 12 22 32 42 52 62 72 8292
[3,]3 13 23 33 43 53 63 73 8393
[4,]4 14 24 34 44 54 64 74 8494
[5,]5 15 25 35 45 55 65 75 8595
[6,]6 16 26 36 46 56 66 76 8696
[7,]7 17 27 37 47 57 67 77 8797
[8,]8 18 28 38 48 58 68 78 8898
[9,]9 19 29 39 49 59 69 79 8999
[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,
Vladimirmailto:[EMAIL PROTECTED]
__
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
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?
[[alternative HTML version deleted]]
__
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
and provide commented, minimal, self-contained, reproducible code.
--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
tel 023-8059-7743
__
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
and provide commented, minimal, self-contained, reproducible code.
Re: [R] how to resample (or resize) matrix?
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 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, Vladimirmailto:[EMAIL PROTECTED] __ 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 and provide commented, minimal, self-contained, reproducible code. __ 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 and provide commented, minimal, self-contained, reproducible code.
Re: [R] how to resample (or resize) matrix?
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 of the surrounding 4 cells?
jh
x - matrix(1:100, 10) # create data
rmean - matrix(0,5,5) # result matrix
for (i in 1:5){
jh + for (j in 1:5){
jh + rmean[i, j] - mean(x[c(-1,0) + 2 * i, c(-1,0) + 2 * j])
jh + }
jh + }
x
jh [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
jh [1,] 1 11 21 31 41 51 61 71 81 91
jh [2,] 2 12 22 32 42 52 62 72 82 92
jh [3,] 3 13 23 33 43 53 63 73 83 93
jh [4,] 4 14 24 34 44 54 64 74 84 94
jh [5,] 5 15 25 35 45 55 65 75 85 95
jh [6,] 6 16 26 36 46 56 66 76 86 96
jh [7,] 7 17 27 37 47 57 67 77 87 97
jh [8,] 8 18 28 38 48 58 68 78 88 98
jh [9,] 9 19 29 39 49 59 69 79 89 99
jh [10,] 10 20 30 40 50 60 70 80 90 100
rmean
jh [,1] [,2] [,3] [,4] [,5]
jh [1,] 6.5 26.5 46.5 66.5 86.5
jh [2,] 8.5 28.5 48.5 68.5 88.5
jh [3,] 10.5 30.5 50.5 70.5 90.5
jh [4,] 12.5 32.5 52.5 72.5 92.5
jh [5,] 14.5 34.5 54.5 74.5 94.5
jh
jh On 7/27/06, Vladimir Eremeev [EMAIL PROTECTED] wrote:Dear r-help,
jh I have a matrix, suppose, 10x10, and I need the matrix 5x5, having
jh in each cell a mean value of the cells from the initial matrix.
jh Please, point me to a function in R, which can help me doing that.
jh Digging the documentation and mail archives didn't give me a result.
jh Thank you.
jh ---
jh Best regards,
jh Vladimirmailto:[EMAIL PROTECTED]
jh __
jh R-help@stat.math.ethz.ch mailing list
jh https://stat.ethz.ch/mailman/listinfo/r-help
jh PLEASE do read the posting guide
jh http://www.R-project.org/posting-guide.html
jh and provide commented, minimal, self-contained, reproducible code.
---
Best regards,
Vladimirmailto:[EMAIL PROTECTED]
==
Research Scientist, PhD Leninsky Prospect 33,
Space Monitoring Ecoinformation Systems Sector, Moscow, Russia, 119071,
Institute of Ecology, Phone: (095) 135-9972;
Russian Academy of Sciences Fax: (095) 135-9972
__
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
and provide commented, minimal, self-contained, reproducible code.
Re: [R] how to resample (or resize) matrix?
Dear Robin, Thank you, seems it is what I need. --- Best regards, Vladimirmailto:[EMAIL PROTECTED] __ 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 and provide commented, minimal, self-contained, reproducible code.
Re: [R] how to resample (or resize) matrix?
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 http://cran.r-project.org/doc/FAQ/R-FAQ.html#Add_002don-packages-from-CRAN SOR and searching down for image The EBImage seems to be able. But I need windows binaries, which are unavailable. SOR cheers, SOR Sean __ 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 and provide commented, minimal, self-contained, reproducible code.
