crossdist              package:spatstat              R Documentation

_P_a_i_r_w_i_s_e _d_i_s_t_a_n_c_e_s _b_e_t_w_e_e_n _t_w_o _d_i_f_f_e_r_e_n_t _p_o_i_n_t _p_a_t_t_e_r_n_s

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

     Computes the distances between pairs of points taken from two
     different point patterns.

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

       crossdist(X, Y, ..., method="C")
       crossdist.ppp(X, Y, ..., method="C")
       crossdist.default(X, Y, x2, y2, ..., method="C")

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

     X,Y: For 'crossdist.ppp', the arguments 'X' and 'Y' should be
          point patterns (objects of class '"ppp"'). For
          'crossdist.default', the arguments 'X' and 'Y' should be
          numeric vectors of equal length specifying the location of
          the first point pattern. 

   x2,y2: For 'crossdist.default', these should be numeric vectors of
          equal length specifying the location of the second point
          pattern. 

     ...: Ignored by 'crossdist.ppp' and 'crossdist.default'. 

  method: String specifying which method of calculation to use. Values
          are '"C"' and '"interpreted"'. 

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

     Given two point patterns,  this function computes the Euclidean
     distance from each point in the first pattern to each point in the
     second pattern, and returns a matrix containing these distances.

     The function 'crossdist' is generic, with a method for point
     patterns (objects of class '"ppp"') and a default method.

     The method for point patterns expects two point patterns 'X' and
     'Y', and returns the matrix whose '[i,j]' entry is the distance
     from 'X[i]' to 'Y[j]'.

     The default method expects 'X' and 'Y' to be numeric vectors of
     equal length specifying the coordinates of the first point
     pattern. The arguments 'x2','y2' specify the coordinates of the
     second point pattern.

     The argument 'method' is not normally used. It is retained only
     for checking the validity of the software. If 'method =
     "interpreted"' then the distances are computed using interpreted R
     code only. If 'method="C"' (the default) then C code is used.  The
     C code is faster by a factor of 4.

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

     A matrix whose '[i,j]' entry is the distance from the 'i'-th point
     in the first pattern to the 'j'-th point in the second pattern.

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

     Pavel Grabarnik pavel.grabar@issp.serpukhov.su and Adrian Baddeley
     adrian@maths.uwa.edu.au <URL:
     http://www.maths.uwa.edu.au/~adrian/>

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

     'pairdist', 'nndist', 'Gest'

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

        data(cells)
        d <- crossdist(cells, runifpoint(6))
        
        d <- crossdist(runif(7), runif(7), runif(12), runif(12))

