ugraph                 package:graph                 R Documentation

_U_n_d_e_r_l_y_i_n_g _G_r_a_p_h

_D_e_s_c_r_i_p_t_i_o_n:

     For a _directed_ graph the underlying graph is the graph that is
     constructed where all edge orientation is ignored. This function
     carries out such a transformation on 'graphNEL' instances.

_U_s_a_g_e:

     ugraph(graph)

_A_r_g_u_m_e_n_t_s:

   graph: a 'graph' object. 

_D_e_t_a_i_l_s:

     If 'graph' is already _undirected_ then it is simply returned.

     If 'graph' is a multi-graph (has multiple edges) an error is
     thrown as it is unclear how to compute the underlying graph in
     that context.

     The method will work for any 'graph' subclass for which an
     'edgeMatrix' method exists.

_V_a_l_u_e:

     An instance of 'graphNEL' with the same nodes as the input but
     which is 'undirected'.

_A_u_t_h_o_r(_s):

     R. Gentleman

_R_e_f_e_r_e_n_c_e_s:

     Graph Theory and its Applications, J. Gross and J. Yellen.

_S_e_e _A_l_s_o:

     'connComp' 'edgeMatrix'

_E_x_a_m_p_l_e_s:

     V <- letters[1:4]
     edL2 <- vector("list", length=4)
     names(edL2) <- V
     for(i in 1:4)
       edL2[[i]] <- list(edges=c(2,1,2,1)[i], weights=sqrt(i))
     gR2 <- new("graphNEL", nodes=V, edgeL=edL2, edgemode="directed")

     ugraph(gR2)

