hi,
I have been trying to do this in R (have implemented it in Excel) but I have
been using a very inefficent way (loops etc.). I have matrix A (columns are
years and ages are rows) and matrix B (columns are birth yrs and rows are
ages)
I would like to first turn matrix A into matrix B
And then I would like to convert matrix B back again to the original matrix
A. (I have left out details of steps) but this is the gist of what I want to
do. Can anyone please give any insights?
Thanks
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Provide a minimal example to start with. This sounds more like voodoo than anything else. Cheers Joris On Fri, May 28, 2010 at 6:30 PM, UM <usman.munir05@imperial.ac.uk> wrote:> > hi, > I have been trying to do this in R (have implemented it in Excel) but I > have > been using a very inefficent way (loops etc.). I have matrix A (columns are > years and ages are rows) and matrix B (columns are birth yrs and rows are > ages) > > > I would like to first turn matrix A into matrix B > > And then I would like to convert matrix B back again to the original matrix > A. (I have left out details of steps) but this is the gist of what I want > to > do. Can anyone please give any insights? > > > Thanks > > > > > > > > > > http://r.789695.n4.nabble.com/file/n2234852/untitled.bmp > > -- > View this message in context: > http://r.789695.n4.nabble.com/Matrix-interesting-question-tp2234852p2234852.html > Sent from the R help mailing list archive at Nabble.com. > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. >-- Joris Meys Statistical Consultant Ghent University Faculty of Bioscience Engineering Department of Applied mathematics, biometrics and process control Coupure Links 653 B-9000 Gent tel : +32 9 264 59 87 Joris.Meys@Ugent.be ------------------------------- Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php [[alternative HTML version deleted]]
Hi, Can you provide sample data? It seems like in both matrices, you have ages in the rows. Do you just want to calculate birth years in matrix B from ages and years in matrix A? It may also help to give us some of the details of what you are doing once you have transformed it prior to transforming back (e.g., are there changes that would impact what the code to convert back needs to be?). Josh On Fri, May 28, 2010 at 9:30 AM, UM <usman.munir05 at imperial.ac.uk> wrote:> > hi, > I have been trying to do this in R (have implemented it in Excel) but I have > been using a very inefficent way (loops etc.). I have matrix A (columns are > years and ages are rows) ?and matrix B (columns are birth yrs and rows are > ages) > > > I would like to first turn matrix A into matrix B > > And then I would like to convert matrix B back again to the original matrix > A. (I have left out details of steps) but this is the gist of what I want to > do. Can anyone please give any insights? > > > Thanks > > > > > > > > > > http://r.789695.n4.nabble.com/file/n2234852/untitled.bmp > > -- > View this message in context: http://r.789695.n4.nabble.com/Matrix-interesting-question-tp2234852p2234852.html > Sent from the R help mailing list archive at Nabble.com. > > ? ? ? ?[[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >-- Joshua Wiley Senior in Psychology University of California, Riverside http://www.joshuawiley.com/
On May 28, 2010, at 12:30 PM, UM wrote:> > hi, > I have been trying to do this in R (have implemented it in Excel) > but I have > been using a very inefficent way (loops etc.). I have matrix A > (columns are > years and ages are rows) and matrix B (columns are birth yrs and > rows are > ages) > > > I would like to first turn matrix A into matrix B >> catrow <- function(A, rn) c(rep("0", 3-rn), A[rn,],rep("0", (2+rn)-3) ) > matrix(sapply(1:3, function(x) catrow(A, x)) , ncol=2*ncol(A)-1, byrow=TRUE) [,1] [,2] [,3] [,4] [,5] [1,] "0" "0" "a" "b" "c" [2,] "0" "d" "e" "f" "0" [3,] "g" "h" "i" "0" "0"> And then I would like to convert matrix B back again to the original > matrix > A.Left as an exercise for the reader.> (I have left out details of steps) but this is the gist of what I > want to > do. Can anyone please give any insights?David Winsemius, MD West Hartford, CT
On 05/29/2010 02:30 AM, UM wrote:> > hi, > I have been trying to do this in R (have implemented it in Excel) but I have > been using a very inefficent way (loops etc.). I have matrix A (columns are > years and ages are rows) and matrix B (columns are birth yrs and rows are > ages) > > > I would like to first turn matrix A into matrix B > > And then I would like to convert matrix B back again to the original matrix > A. (I have left out details of steps) but this is the gist of what I want to > do. Can anyone please give any insights? > >Hi UM, The answer is somewhat trivial (see below) but my initial misunderstanding of the question led me to write a function that I have often wanted. When using an "apply" family function, I sometimes want to apply a different argument to each slice of the object. I'm pretty sure that this has been done before, and I even looked through the "plyr" package but couldn't find what I wanted. Here's an example for a data frame. dfapply2<-function(x,FUN,args) { dimx<-dim(x) newx<-list() for(column in 1:dimx[2]) newx[[column]]<-do.call(FUN,list(x[column],args[column])) names(newx)<-names(x) return(as.data.frame(newx)) } Pretty rough, but it does apply the arguments in "args" to the respective columns. So, thanks for motivating me to program this. Jim digahole<-function(x) { dimx<-dim(x) years<-as.numeric(colnames(x)) ages<-as.numeric(rownames(x)) minby<-min(years)-max(ages) maxby<-max(years)-min(ages) newx<-matrix(NA,nrow=dimx[1],ncol=1+maxby-minby) rownames(newx)<-rownames(x) colnames(newx)<-minby:maxby oldrow<-rep(1:dimx[1],each=dimx[2]) oldcol<-rep(1:dimx[2],dimx[1]) newcol<-oldcol+rep(max(ages)-ages,each=dimx[1]) for(element in 1:length(oldrow)) newx[oldrow[element],newcol[element]]<-x[oldrow[element],oldcol[element]] return(newx) } fillitup<-function(x) { dimx<-dim(x) byears<-as.numeric(colnames(x)) ages<-as.numeric(rownames(x)) minyr<-min(byears)+max(ages) maxyr<-max(byears)+min(ages) oldx<-matrix(NA,nrow=dimx[1],ncol=1+maxyr-minyr) rownames<-rownames(x) colnames<-minyr:maxyr for(row in 1:dimx[1]) oldx[row,]<-x[row,which(!is.na(x[row,]))] return(oldx) } fillitup(digahole(A))