dendrogram {stats} | R Documentation |
Class "dendrogram"
provides general functions for handling
tree-like structures. It is intended as a replacement for similar
functions in hierarchical clustering and classification/regression
trees, such that all of these can use the same engine for plotting or
cutting trees.
The code is still in testing stage and the API may change in the future.
as.dendrogram(object, ...)
## S3 method for class 'hclust'
as.dendrogram(object, hang = -1, ...)
## S3 method for class 'dendrogram'
plot(x, type = c("rectangle", "triangle"),
center = FALSE,
edge.root = is.leaf(x) || !is.null(attr(x,"edgetext")),
nodePar = NULL, edgePar = list(),
leaflab = c("perpendicular", "textlike", "none"),
dLeaf = NULL, xlab = "", ylab = "", xaxt = "n", yaxt = "s",
horiz = FALSE, frame.plot = FALSE, xlim, ylim, ...)
## S3 method for class 'dendrogram'
cut(x, h, ...)
## S3 method for class 'dendrogram'
print(x, digits, ...)
## S3 method for class 'dendrogram'
rev(x)
## S3 method for class 'dendrogram'
str(object, max.level = NA, digits.d = 3,
give.attr = FALSE, wid = getOption("width"),
nest.lev = 0, indent.str = "", stem = "--", ...)
is.leaf(object)
object |
any R object that can be made into one of class
|
x |
object of class |
hang |
numeric scalar indicating how the height of leaves
should be computed from the heights of their parents; see
|
type |
type of plot. |
center |
logical; if |
edge.root |
logical; if true, draw an edge to the root node. |
nodePar |
a |
edgePar |
a |
leaflab |
a string specifying how leaves are labeled. The
default |
dLeaf |
a number specifying the distance in user
coordinates between the tip of a leaf and its label. If |
horiz |
logical indicating if the dendrogram should be drawn horizontally or not. |
frame.plot |
logical indicating if a box around the plot should
be drawn, see |
h |
height at which the tree is cut. |
xlim , ylim |
optional x- and y-limits of the plot, passed to
|
... , xlab , ylab , xaxt , yaxt |
graphical parameters, or arguments for other methods. |
digits |
integer specifying the precision for printing, see
|
max.level , digits.d , give.attr , wid , nest.lev , indent.str |
arguments to |
stem |
a string used for |
Warning: This documentation is preliminary.
The dendrogram is directly represented as a nested list where each
component corresponds to a branch of the tree. Hence, the first
branch of tree z
is z[[1]]
, the second branch of the
corresponding subtree is z[[1]][[2]]
etc.. Each node of the tree
carries some information needed for efficient plotting or cutting as
attributes, of which only members
, height
and
leaf
for leaves are compulsory:
members
total number of leaves in the branch
height
numeric non-negative height at which the node is plotted.
midpoint
numeric horizontal distance of the node from
the left border (the leftmost leaf) of the branch (unit 1 between
all leaves). This is used for plot(*, center=FALSE)
.
label
character; the label of the node
x.member
for cut()$upper
,
the number of former members; more generally a substitute
for the members
component used for ‘horizontal’
(when horiz = FALSE
, else ‘vertical’) alignment.
edgetext
character; the label for the edge leading to the node
nodePar
a named list (of length-1 components)
specifying node-specific attributes for points
plotting, see the nodePar
argument above.
edgePar
a named list (of length-1 components)
specifying attributes for segments
plotting of the
edge leading to the node, and drawing of the edgetext
if
available, see the edgePar
argument above.
leaf
logical, if TRUE
, the node is a leaf of
the tree.
cut.dendrogram()
returns a list with components $upper
and $lower
, the first is a truncated version of the original
tree, also of class dendrogram
, the latter a list with the
branches obtained from cutting the tree, each a dendrogram
.
There are [[
, print
, and str
methods for "dendrogram"
objects where the first one
(extraction) ensures that selecting sub-branches keeps the class.
Objects of class "hclust"
can be converted to class
"dendrogram"
using method as.dendrogram
.
rev.dendrogram
simply returns the dendrogram x
with
reversed nodes, see also reorder.dendrogram
.
is.leaf(object)
is logical indicating if object
is a
leaf (the most simple dendrogram).
plotNode()
and plotNodeLimit()
are helper functions.
Some operations on dendrograms (including plotting) make use of
recursion. For very deep trees It may be necessary to increase
options("expressions")
: if you do you are likely to need
to set the C stack size larger than the OS default if possible
(which it is not on Windows).
When using type = "triangle"
, center = TRUE
often looks
better.
order.dendrogram
also on the labels
method
for dendrograms.
require(graphics); require(utils)
hc <- hclust(dist(USArrests), "ave")
(dend1 <- as.dendrogram(hc)) # "print()" method
str(dend1) # "str()" method
str(dend1, max = 2) # only the first two sub-levels
op <- par(mfrow= c(2,2), mar = c(5,2,1,4))
plot(dend1)
## "triangle" type and show inner nodes:
plot(dend1, nodePar=list(pch = c(1,NA), cex=0.8, lab.cex = 0.8),
type = "t", center=TRUE)
plot(dend1, edgePar=list(col = 1:2, lty = 2:3),
dLeaf=1, edge.root = TRUE)
plot(dend1, nodePar=list(pch = 2:1,cex=.4*2:1, col = 2:3),
horiz=TRUE)
dend2 <- cut(dend1, h=70)
plot(dend2$upper)
## leafs are wrong horizontally:
plot(dend2$upper, nodePar=list(pch = c(1,7), col = 2:1))
## dend2$lower is *NOT* a dendrogram, but a list of .. :
plot(dend2$lower[[3]], nodePar=list(col=4), horiz = TRUE, type = "tr")
## "inner" and "leaf" edges in different type & color :
plot(dend2$lower[[2]], nodePar=list(col=1),# non empty list
edgePar = list(lty=1:2, col=2:1), edge.root=TRUE)
par(op)
str(d3 <- dend2$lower[[2]][[2]][[1]])
## "Zoom" in to the first dendrogram :
plot(dend1, xlim = c(1,20), ylim = c(1,50))
nP <- list(col=3:2, cex=c(2.0, 0.75), pch= 21:22,
bg= c("light blue", "pink"),
lab.cex = 0.75, lab.col = "tomato")
plot(d3, nodePar= nP, edgePar = list(col="gray", lwd=2), horiz = TRUE)
addE <- function(n) {
if(!is.leaf(n)) {
attr(n, "edgePar") <- list(p.col="plum")
attr(n, "edgetext") <- paste(attr(n,"members"),"members")
}
n
}
d3e <- dendrapply(d3, addE)
plot(d3e, nodePar= nP)
plot(d3e, nodePar= nP, leaflab = "textlike")