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: An instance of 'graphNEL'. 

_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.

_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'

_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)

