- for (i in 2:length(x)) {
- label <- x[[i]]$tip.label
- if (!identical(label, ref)) {
- if (length(label) != length(ref))
- stop(paste("tree no.", i, "has a different number of tips"))
- ilab <- match(label, ref)
- ## can use tabulate here because 'ilab' contains integers
- if (any(is.na(ilab)))
- stop(paste("tree no.", i, "has different tip labels"))
+ Ntree <- length(x)
+ if (Ntree > 1) {
+ for (i in 2:Ntree) {
+ label <- x[[i]]$tip.label
+ if (!identical(label, ref)) {
+ if (length(label) != length(ref))
+ stop(paste("tree no.", i, "has a different number of tips"))
+ ilab <- match(label, ref)
+ ## can use tabulate here because 'ilab' contains integers
+ if (any(is.na(ilab)))
+ stop(paste("tree no.", i, "has different tip labels"))