Parameters :  Z : ndarray
The linkage matrix encoding the hierarchical clustering to
render as a dendrogram. See the linkage function for more
information on the format of Z.
p : int, optional
The p parameter for truncate_mode.
truncate_mode : str, optional
The dendrogram can be hard to read when the original
observation matrix from which the linkage is derived is
large. Truncation is used to condense the dendrogram. There
are several modes:
 None/’none’: no truncation is performed (Default)
 ‘lastp’: the last p nonsingleton formed in the linkage
are the only nonleaf nodes in the linkage; they correspond
to to rows Z[np2:end] in Z. All other
nonsingleton clusters are contracted into leaf nodes.
 ‘mlab’: This corresponds to MATLAB(TM) behavior. (not
implemented yet)
 ‘level’/’mtica’: no more than p levels of the
dendrogram tree are displayed. This corresponds to
Mathematica(TM) behavior.
color_threshold : double, optional
get_leaves : bool, optional
orientation : str, optional
The direction to plot the dendrogram, which can be any
of the following strings:
 ‘top’ plots the root at the top, and plot descendent
links going downwards. (default).
 ‘bottom’ plots the root at the bottom, and plot descendent
links going upwards.
 ‘left’ plots the root at the left, and plot descendent
links going right.
 ‘right’ plots the root at the right, and plot descendent
links going left.
labels : ndarray, optional
By default labels is None so the index of the
original observation is used to label the leaf nodes.
Otherwise, this is an sized list (or tuple). The
labels[i] value is the text to put under the th
leaf node only if it corresponds to an original observation
and not a nonsingleton cluster.
count_sort : str or bool, optional
For each node n, the order (visually, from lefttoright) n’s
two descendent links are plotted is determined by this
parameter, which can be any of the following values:
 False: nothing is done.
 ‘ascending’/True: the child with the minimum number of
original objects in its cluster is plotted first.
 ‘descendent’: the child with the maximum number of
original objects in its cluster is plotted first.
Note distance_sort and count_sort cannot both be
True.
distance_sort : str or bool, optional
For each node n, the order (visually, from lefttoright) n’s
two descendent links are plotted is determined by this
parameter, which can be any of the following values:
 False: nothing is done.
 ‘ascending’/True: the child with the minimum distance
between its direct descendents is plotted first.
 ‘descending’: the child with the maximum distance
between its direct descendents is plotted first.
Note distance_sort and count_sort cannot both be
True.
show_leaf_counts : bool, optional
When True, leaf nodes representing original
observation are labeled with the number of observations they
contain in parentheses.
no_plot : bool, optional
When True, the final rendering is not performed. This is
useful if only the data structures computed for the rendering
are needed or if matplotlib is not available.
no_labels : bool, optional
When True, no labels appear next to the leaf nodes in the
rendering of the dendrogram.
leaf_label_rotation : double, optional
Specifies the angle (in degrees) to rotate the leaf
labels. When unspecified, the rotation based on the number of
nodes in the dendrogram. (Default=0)
leaf_font_size : int, optional
Specifies the font size (in points) of the leaf labels. When
unspecified, the size based on the number of nodes in the
dendrogram.
leaf_label_func : lambda or function, optional
When leaf_label_func is a callable function, for each
leaf with cluster index . The function
is expected to return a string with the label for the
leaf.
Indices correspond to original observations
while indices correspond to nonsingleton
clusters.
For example, to label singletons with their node id and
nonsingletons with their id, count, and inconsistency
coefficient, simply do:
# First define the leaf label function.
def llf(id):
if id < n:
return str(id)
else:
return '[%d %d %1.2f]' % (id, count, R[nid,3])
# The text for the leaf nodes is going to be big so force
# a rotation of 90 degrees.
dendrogram(Z, leaf_label_func=llf, leaf_rotation=90)
show_contracted : bool
When True the heights of nonsingleton nodes contracted
into a leaf node are plotted as crosses along the link
connecting that leaf node. This really is only useful when
truncation is used (see truncate_mode parameter).
link_color_func : lambda/function
When a callable function,
link_color_function is called with each nonsingleton id
corresponding to each Ushaped link it will paint. The
function is expected to return the color to paint the link,
encoded as a matplotlib color string code.
For example:
>>> dendrogram(Z, link_color_func=lambda k: colors[k])
colors the direct links below each untruncated nonsingleton node
k using colors[k].

Returns :  R : dict
A dictionary of data structures computed to render the
dendrogram. Its has the following keys:
 ‘icoords’: a list of lists [I1, I2, ..., Ip] where
Ik is a list of 4 independent variable coordinates
corresponding to the line that represents the k’th link
painted.
 ‘dcoords’: a list of lists [I2, I2, ..., Ip] where
Ik is a list of 4 independent variable coordinates
corresponding to the line that represents the k’th link
painted.
 ‘ivl’: a list of labels corresponding to the leaf nodes.
 ‘leaves’: for each i, H[i] == j, cluster node
appears in the th position in the
lefttoright traversal of the leaves, where
and . If is less than , the
th leaf node corresponds to an original
observation. Otherwise, it corresponds to a nonsingleton
cluster.
