-## rtree.R (2009-11-03)
+## rtree.R (2010-03-09)
-## Generates Random Trees
+## Generates Trees
-## Copyright 2004-2009 Emmanuel Paradis
+## Copyright 2004-2010 Emmanuel Paradis
## This file is part of the R-package `ape'.
## See the file ../COPYING for licensing issues.
class(a) <- "multiPhylo"
a
}
+
+stree <- function(n, type = "star", tip.label = NULL)
+{
+ type <- match.arg(type, c("star", "balanced", "left", "right"))
+ n <- as.integer(n)
+ if (type == "star") {
+ N <- n
+ m <- 1L
+ } else {
+ m <- n - 1L
+ N <- n + m - 1L
+ }
+ edge <- matrix(0L, N, 2)
+
+ switch(type, "star" = {
+ edge[, 1] <- n + 1L
+ edge[, 2] <- 1:n
+ }, "balanced" = {
+ if (log2(n) %% 1)
+ stop("'n' is not a power of 2: cannot make a balanced tree")
+ foo <- function(node, size) {
+ if (size == 2) {
+ edge[c(i, i + 1L), 1L] <<- node
+ edge[c(i, i + 1L), 2L] <<- c(nexttip, nexttip + 1L)
+ nexttip <<- nexttip + 2L
+ i <<- i + 2L
+ } else {
+ for (k in 1:2) { # do the 2 subclades
+ edge[i, ] <<- c(node, nextnode)
+ nextnode <<- nextnode + 1L
+ i <<- i + 1L
+ foo(nextnode - 1L, size/2)
+ }
+ }
+ }
+ i <- 1L
+ nexttip <- 1L
+ nextnode <- n + 2L
+ foo(n + 1L, n)
+ }, "left" = {
+ edge[c(seq.int(from = 1, to = N - 1, by = 2), N), 2L] <- 1:n
+ nodes <- (n + 1L):(n + m)
+ edge[seq.int(from = 2, to = N - 1, by = 2), 2L] <- nodes[-1]
+ edge[, 1L] <- rep(nodes, each = 2)
+ }, "right" = {
+ nodes <- (n + 1L):(n + m)
+ edge[, 1L] <- c(nodes, rev(nodes))
+ edge[, 2L] <- c(nodes[-1], 1:n)
+ })
+
+ if (is.null(tip.label))
+ tip.label <- paste("t", 1:n, sep = "")
+ phy <- list(edge = edge, tip.label = tip.label, Nnode = m)
+ class(phy) <- "phylo"
+ attr(phy, "order" <- "cladewise")
+ phy
+}