Ordering                package:RBGL                R Documentation

_C_o_m_p_u_t_e _v_e_r_t_e_x _o_r_d_e_r_i_n_g _f_o_r _a_n _u_n_d_i_r_e_c_t_e_d _g_r_a_p_h

_D_e_s_c_r_i_p_t_i_o_n:

     Compute vertex ordering for an undirected graph

_U_s_a_g_e:

     cuthill.mckee.ordering(g)
     minDegreeOrdering(g, delta=0)
     sloan.ordering(g, w1=1, w2=2)

_A_r_g_u_m_e_n_t_s:

       g: an instance of the 'graph' class with 'edgemode' "undirected"

   delta: Multiple elimination control variable. If it is larger than
          or  equal to zero then multiple elimination is enabled. The
          value of delta  specifies the difference between the minimum
          degree and the degree of  vertices that are to be eliminated.

      w1: 1st Heuristical weight for the Sloan algorithm 

      w2: 2nd Heuristical weight for the Sloan algorithm 

_D_e_t_a_i_l_s:

     According to the documentations on these algorithms in Boost Graph
     Library:

     The goal of the Cuthill-Mckee (and reverse Cuthill-Mckee) ordering
     algorithm is to reduce the bandwidth of a graph by reordering the
     indices assigned to each vertex. 

     The minimum degree ordering algorithm is a fill-in reduction
     matrix reordering algorithm. 

     The goal of the Sloan ordering algorithm is to reduce the profile
     and the wavefront of a graph by reordering the indices assigned to
     each vertex. 

     The goal of the King ordering algorithm is to reduce the bandwidth
     of a graph  by reordering the indices assigned to each vertex.

     See documentations on these algorithms in Boost Graph Library for
     more details.

_V_a_l_u_e:

cuthill.mckee.ordering: returns a list with elements:

reverse cuthill.mckee.ordering: the vertices in the new ordering

original bandwidth: bandwidth before reordering vertices

new bandwidth: bandwidth after reordering of vertices

minDegreeOrdering: return a list with elements:

inverse_permutation: the new vertex ordering, given as the mapping from
          the new indices to the old indices 

permutation: the new vertex ordering, given as the mapping from the old
          indices to the new indices 

sloan.ordering: returns a list with elements:

sloan.ordering: the vertices in the new ordering

bandwidth: bandwidth of the graph after reordering

 profile: profile of the graph after reordering

maxWavefront: maxWavefront of the graph after reordering

aver.wavefront: aver.wavefront of the graph after reordering

rms.wavefront: rms.wavefront of the graph after reordering

_A_u_t_h_o_r(_s):

     Li Long <li.long@isb-sib.ch>

_R_e_f_e_r_e_n_c_e_s:

     Boost Graph Library by Siek et al.

_S_e_e _A_l_s_o:

_E_x_a_m_p_l_e_s:

     coex <- fromGXL(file(system.file("XML/dijkex.gxl",package="RBGL"), open="r"))
     coex <- ugraph(coex)
     cuthill.mckee.ordering(coex)
     minDegreeOrdering(coex)
     sloan.ordering(coex)

