Poisson               package:spatstat               R Documentation

_P_o_i_s_s_o_n _P_o_i_n_t _P_r_o_c_e_s_s _M_o_d_e_l

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

     Creates an instance of the Poisson point process model which can
     then be fitted to point pattern data.

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

      Poisson()

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

     The function 'ppm()', which fits point process models to  point
     pattern data, requires an argument 'interaction' of class
     '"interact"' describing the interpoint interaction structure of
     the model to be fitted.  The appropriate description of the
     Poisson process is  provided by the value of the function
     'Poisson()'.

     This works for all types of Poisson processes including multitype
     and nonstationary Poisson processes.

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

     An object of class '"interact"' describing the interpoint
     interaction  structure of the Poisson point process (namely, there
     are no interactions).

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

     Adrian Baddeley adrian@maths.uwa.edu.au <URL:
     http://www.maths.uwa.edu.au/~adrian/> and Rolf Turner
     rolf@math.unb.ca <URL: http://www.math.unb.ca/~rolf>

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

     'Strauss', 'StraussHard'

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

      data(nztrees)
      ppm(nztrees, ~1, Poisson())
      # fit the stationary Poisson process to 'nztrees'
      # no edge correction needed

      data(longleaf)
      
      longadult <- longleaf[longleaf$marks >= 30, ]
      longadult <- unmark(longadult)
      ppm(longadult, ~ x, Poisson())
      # fit the nonstationary Poisson process 
      # with intensity lambda(x,y) = exp( a + bx)

      data(lansing)
      # trees marked by species
      
      ppm(lansing, ~ marks, Poisson())
      # fit stationary marked Poisson process
      # with different intensity for each species

     ## Not run: 
      ppm(lansing, ~ marks * polynom(x,y,3), Poisson())
     ## End(Not run)
      # fit nonstationary marked Poisson process
      # with different log-cubic trend for each species

