balKfold.xvspec {MLInterfaces} | R Documentation |
generate a partition function for cross-validation, where the partitions are approximately balanced with respect to the distribution of a response variable
balKfold.xvspec(K)
K |
number of partitions to be computed |
This function returns a closure. The symbol K
is
bound in the environment of the returned function.
A closure consisting of a function that can be used
as a partitionFunc
for passage in xvalSpec
.
VJ Carey <stvjc@channing.harvard.edu>
## The function is currently defined as function (K) function(data, clab, iternum) { clabs <- data[[clab]] narr <- nrow(data) cnames <- unique(clabs) ilist <- list() for (i in 1:length(cnames)) ilist[[cnames[i]]] <- which(clabs == cnames[i]) clens <- lapply(ilist, length) nrep <- lapply(clens, function(x) ceiling(x/K)) grpinds <- list() for (i in 1:length(nrep)) grpinds[[i]] <- rep(1:K, nrep[[i]])[1:clens[[i]]] (1:narr)[-which(unlist(grpinds) == iternum)] } # try it out data(crabs) p1c = balKfold.xvspec(5) inds = p1c( crabs, "sp", 3 ) table(crabs$sp[inds] ) inds2 = p1c( crabs, "sp", 4 ) table(crabs$sp[inds2] ) allc = 1:200 # are test sets disjoint? intersect(setdiff(allc,inds), setdiff(allc,inds2))