UScounties               package:spam               R Documentation

_A_d_j_a_c_e_n_c_y _s_t_r_u_c_t_u_r_e _o_f _t_h_e _c_o_u_n_t_i_e_s _i_n _t_h_e _c_o_n_t_i_g_u_o_u_s _U_n_i_t_e_d _S_t_a_t_e_s

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

     First and second order adjacency structure of the counties in the
     contiguous United States. We consider that two counties are
     neighbors if they share at least one edge of their polygon
     description in 'maps'.

_F_o_r_m_a_t:

     Two matrices of class 'spam'


     _U_S_c_o_u_n_t_i_e_s._s_t_o_r_d_e_r Contains a one in the 'i' and 'j' element if 
          county 'i' is a neighbor of county 'j'.

     _U_S_c_o_u_n_t_i_e_s._n_d_o_r_d_e_r Contains a one in the 'i' and 'j' element if 
          counties 'i' and 'j' are a neighbors of county 'k' and
          counties  'i' and 'j'  are not  neighbors.


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

     'map'

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

     # number of counties:
     n  <- nrow( UScounties.storder)

     ## Not run: 
     # make a precision matrix 
     Q <- diag.spam( n) + .2 * UScounties.storder + .1 * UScounties.ndorder
     display( as.spam( chol( Q)))
     ## End(Not run)

