Interesting variety of solutions! Thanks very much. Murali
-----Original Message----- From: Henrique Dallazuanna [mailto:www...@gmail.com] Sent: 31 March 2011 18:26 To: Menon Murali Cc: r-help@r-project.org Subject: Re: [R] choosing best 'match' for given factor Try this: bestMatch <- function(search, match) { colnames(match)[pmax(apply(match[,search], 2, which.max) - 1, 1)] } On Thu, Mar 31, 2011 at 11:46 AM, <murali.me...@avivainvestors.com> wrote: > Folks, > > I have a 'matching' matrix between variables A, X, L, O: > >> a <- structure(c(1, 0.41, 0.58, 0.75, 0.41, 1, 0.6, 0.86, 0.58, > 0.6, 1, 0.83, 0.75, 0.86, 0.83, 1), .Dim = c(4L, 4L), .Dimnames = list( > c("A", "X", "L", "O"), c("A", "X", "L", "O"))) > >> a > A X L O > A 1.00 0.41 0.58 0.75 > X 0.41 1.00 0.60 0.86 > L 0.58 0.75 1.00 0.83 > O 0.60 0.86 0.83 1.00 > > And I have a search vector of variables > >> v <- c("X", "O") > > I want to write a function bestMatch(searchvector, matchMat) such that for > each variable in searchvector, I get the variable that it has the highest > match to - but searching only among variables to the left of it in the > 'matching' matrix, and not matching with any variable in searchvector itself. > > So in the above example, although "X" has the highest match (0.86) with "O", > I can't choose "O" as it's to the right of X (and also because "O" is in the > searchvector v already); I'll have to choose "A". > > For "O", I will choose "L", the variable it's best matched with - as it can't > match "X" already in the search vector. > > My function bestMatch(v, a) will then return c("A", "L") > > My matrix a is quite large, and I have a long list of search vectors v, so I > need an efficient method. > > I wrote this: > > bestMatch <- function(searchvector, matchMat) { > sapply(searchvector, function(cc) { > y <- matchMat[!(rownames(matchMat) %in% > searchvector) & (index(rownames(matchMat)) < match(cc, rownames(matchMat))), > cc, drop = FALSE]; > rownames(y)[which.max(y)] > }) > } > > Any advice? > > Thanks, > > Murali > > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ 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.
