dendrogram                package:mva                R Documentation

_G_e_n_e_r_a_l _T_r_e_e _S_t_r_u_c_t_u_r_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     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. Currently the code is in alpha stage and the API
     may change at any point in time.

_U_s_a_g_e:

     plot.dendrogram(dobj, type=c("rectangle", "triangle"),
                     center=FALSE, xlab="", ylab="", ...)
     as.dendrogram.hclust(object, ...)
     cut.dendrogram(dobj, h)

     plotNode(x1, x2, subtree, type, center)
     plotNodeLimit(x1, x2, subtree, center)

_A_r_g_u_m_e_n_t_s:

    dobj: Object of class `"dendrogram"'.

    type: Type of plot.

  center: If `TRUE', nodes are plotted centered with respect to the
          leaves in the branch. Default is to plot them in the middle
          of all direct child nodes.

       h: Height at which the tree is cutted.

_D_e_t_a_i_l_s:

     Warning: This documentation is preliminary.

     The dendrogram is directly represented as a nested list, where
     each list 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:

     `_m_e_m_b_e_r_s' number of leaves in the branch

     `_h_e_i_g_h_t' Height at which the node is plotted

     `_m_i_d_p_o_i_n_t' Horizontal distance of the node from the left border of
          the branch

     `_t_e_x_t' Text label of the node

     _e_d_g_e_t_e_x_t Text label for the edge leading to the node

     Terminal nodes (leaves of the tree) can have arbitrary value but
     must not be a list.

     `cut.dendrogram()' returns a list with components `$upper' and
     `$lower', the first is a truncated version of the original tree,
     the latter a list with the branches obtained from cutting the
     tree.

     `plotNode()' and `plotNodeLimit()' are helper functions.

_E_x_a_m_p_l_e_s:

     library(mva)
     data(USArrests)
     hc <- hclust(dist(USArrests), "ave")
     str(dend1 <- as.dendrogram(hc))
     plot(dend1)
     dend2 <- cut(dend1, h=70)
     plot(dend2$upper)
     plot(dend2$lower[[3]])

