## collapse.singles.R (2010-07-23)
## Collapse "Single" Nodes
## Copyright 2006 Ben Bolker
## This file is part of the R-package `ape'.
## See the file ../COPYING for licensing issues.
collapse.singles <- function(tree)
{
elen <- tree$edge.length
xmat <- tree$edge
## added by Elizabeth Purdom (2008-06-19):
node.lab <- tree$node.label
nnode <- tree$Nnode
ntip <- length(tree$tip.label)
## end
singles <- NA
while (length(singles) > 0) {
## changed by EP to make it slightly more efficient:
## tx <- table(xmat[xmat < 0])
## singles <- as.numeric(names(tx)[tx < 3])
tx <- tabulate(xmat[, 1])
singles <- which(tx == 1)
## END
if (length(singles) > 0) {
i <- singles[1]
prev.node <- which(xmat[, 2] == i)
next.node <- which(xmat[, 1] == i)
xmat[prev.node, 2] <- xmat[next.node, 2]
xmat <- xmat[xmat[, 1] != i, ] # drop
## changed by EP for the new coding of "phylo" (2006-10-05):
## xmat[xmat < i] <- xmat[xmat < i] + 1 ## adjust indices
xmat[xmat > i] <- xmat[xmat > i] - 1L ## adjust indices # changed '1' by '1L' (2010-07-23)
## END
elen[prev.node] <- elen[prev.node] + elen[next.node]
## added by Elizabeth Purdom (2008-06-19):
if (!is.null(node.lab)) node.lab <- node.lab[-c(i - ntip)]
nnode <- nnode - 1L
## end
elen <- elen[-next.node]
}
}
tree$edge <- xmat
tree$edge.length <- elen
## added by Elizabeth Purdom (2008-06-19):
tree$node.label <- node.lab
tree$Nnode <- nnode
## end
tree
}
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