Oops. My error! You wanted a 2D filter. I suspect a search will find some implementation, but you may wish to consider ?loess instead (there are numerous others, no doubt).
-- Bert On Sun, Mar 27, 2011 at 3:30 PM, David Winsemius <dwinsem...@comcast.net> wrote: > > On Mar 27, 2011, at 1:07 PM, Mike Marchywka wrote: > >> You obviously want to delegate inner loops to R packages that >> execute as native, hopefully optimized, code. >> Generally a google search that starts with "R CRAN" will help. >> In this case it looks like a few packages available, >>> >> http://www.google.com/search?sclient=psy&hl=en&q=R+cran+median+filter > > Did you find any that include a 2D median filter? All the ones I looked at > were for univariate data. > > -- > David. > > >>> >>> ---------------------------------------- >>>> >>>> Date: Sun, 27 Mar 2011 07:56:11 -0700 >>>> From: chuan...@hotmail.com >>>> To: r-help@r-project.org >>>> Subject: [R] Asking Favor For the Script of Median Filter >>>> >>>> Hello,everybody. My name is Chuan Zun Liang. I come from Malaysia. I am >>>> just >>>> a beginner for R. Kindly to ask favor about median filter. The problem I >>>> facing as below: >>>> >>>> >>>>> x<-matrix(sample(1:30,25),5,5) >>>>> x >>>> >>>> [,1] [,2] [,3] [,4] [,5] >>>> [1,] 7 8 30 29 13 >>>> [2,] 4 6 12 5 9 >>>> [3,] 25 3 22 14 24 >>>> [4,] 2 15 26 23 19 >>>> [5,] 28 18 10 11 20 >>>> >>>> This is example original matrices of an image. I want apply with median >>>> filter with window size 3X# to remove salt and pepper noise in my >>>> matric. >>>> Here are the script I attend to writing.The script and output shown as >>>> below: >>>> >>>>> MedFilter<-function(mat,sz) >>>> >>>> + {out<-matrix(0,nrow(mat),ncol(mat)) >>>> + for(p in 1:(nrow(mat)-(sz-1))) >>>> + {for(q in 1:(ncol(mat)-(sz-1))) >>>> + {outrow<-median(as.vector(mat[p:(p+(sz-1)),q:(q+(sz-1))])) >>>> + out[(p+p+(sz-1))/2,(q+q+(sz-1))/2]<-outrow}} >>>> + out} >>>> >>>>> MedFilter(x,3) >>>> >>>> [,1] [,2] [,3] [,4] [,5] >>>> [1,] 0 0 0 0 0 >>>> [2,] 0 8 12 14 0 >>>> [3,] 0 12 14 19 0 >>>> [4,] 0 18 15 20 0 >>>> [5,] 0 0 0 0 0 >>>> >>>> Example to getting value 8 and 12 as below: >>>> >>>> 7 8 30 8 30 29 >>>> 4 6 12 (median=8) 6 12 5 (median=12) >>>> 25 3 22 3 22 14 >>>> >>>> Even the script can give output. However, it is too slow. My image size >>>> is >>>> 364*364. It is time consumption. Is it get other ways to improving it? >>>> >>>> Best Wishes >>>> Chuan > > > -- > David Winsemius, MD > West Hartford, CT > > ______________________________________________ > R-help@r-project.org 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. > -- Bert Gunter Genentech Nonclinical Biostatistics ______________________________________________ R-help@r-project.org 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.
