elgorgonzola wrote: > > Hi, > > i am working on a problem where i need to compute the products of all > possible combinations of size m of the elements of a vector. I know that > this can be achieved using the function combn(), e.g.: > >> vector <- 1:6 >> combn(x = vector, m = 3, FUN = function(y) prod(y)) > > In my case the vector has 2000 elements and i need to compute the values > specified above for m = 32. Using combn() i encounter problems for m >= 4. > Is there any alternative to combn() that works more efficiently? Also my > vector contains many duplicates, so there are actually only about 300 > distinct values in the vector. This reduces the number of possible > combinations significantly. Is there any way to use this fact to reduce > the computational cost? > > Thanks in advance, > > El >
The unique() function can be used to quickly filter out duplicates in your input function. I am not aware of an alternative implementation of combn(), but that doesn't mean there isn't one out there. Good luck! -Charlie ----- Charlie Sharpsteen Undergraduate-- Environmental Resources Engineering Humboldt State University -- View this message in context: http://n4.nabble.com/More-efficient-alternative-to-combn-tp1692117p1692128.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
