# fields, Tools for spatial data # Copyright 2004-2007, Institute for Mathematics Applied Geosciences # University Corporation for Atmospheric Research # Licensed under the GPL -- www.gpl.org/licenses/gpl.html "cat.to.list" <- function (x, a) { a <- as.character(a) label <- unique(a) out <- as.list(1:length(label)) names(out) <- label for (k in 1:length(label)) { out[[k]] <- x[label[k] == a] if (length(out[[k]]) == 0) out[[k]] <- NA } out }