variog4                 package:geoR                 R Documentation

_C_o_m_p_u_t_e_s _D_i_r_e_c_t_i_o_n_a_l _V_a_r_i_o_g_r_a_m_s

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

     Computes directional variograms for 4 directions provided by the
     user.

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

     variog4(geodata, coords = geodata$coords, data = geodata$data,
             uvec = "default", trend = "cte", lambda = 1,
             option = c("bin", "cloud", "smooth"),
             estimator.type = c("classical", "modulus"),
             nugget.tolerance = 0, max.dist = NULL, pairs.min = 2,
             bin.cloud = FALSE, direction = c(0, pi/4, pi/2, 3*pi/4),
             tolerance = pi/8, unit.angle = c("radians", "degrees"),
             messages.screen = TRUE, ...)

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

     Most arguments are the same as for the function `variog'. The only
     exception is the following. 

direction: a vector with values of 4 angles, indicating the directions
          for which the variograms will be computed. Defaults to `c(0,
          45, 90, 135)' (degrees). 

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

     The output is an object of the class `variog4', a list with five
     components. The first four elements are estimated variograms for
     the directions provided and the last is the omnidirectional
     variogram.  Each individual component is an object of the class
     `variogram', an output of the function `variog'.

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

     Paulo J. Ribeiro Jr. Paulo.Ribeiro@est.ufpr.br, 
     Peter J. Diggle p.diggle@lancaster.ac.uk.

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

     Further information about geoR can be found at:
     <URL: http://www.maths.lancs.ac.uk/~ribeiro/geoR.html>.

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

     `variog' for variogram calculations and `plot.variog4' for
     plotting results

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

     if(is.R()) data(s100)
     var4 <- variog4(s100, max.dist=1)
     plot(var4)

