nndist               package:spatstat               R Documentation

_N_e_a_r_e_s_t _n_e_i_g_h_b_o_u_r _d_i_s_t_a_n_c_e_s

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

     Computes the distance from each point to its nearest neighbour in
     a point pattern.

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

       nndist(x, y=NULL, method="C")

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

     x,y: Arguments specifying the x and y coordinates of a set of
          points. Typically 'x' and 'y' would be numeric vectors of
          equal length. Alternatively 'y' may be omitted and 'x' may be
          a point pattern (object of class '"ppp"') or a list with two
          components 'x' and 'y', or a matrix with two columns. 

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

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

     This function computes the Euclidean distance from each point in a
     point pattern to its nearest neighbour (the nearest other point of
     the pattern).

     If 'method = "interpreted"' then the distances are computed using
     interpreted R code only. If 'method="C"' then C code is used. The
     C code is faster by two to three orders of magnitude and uses much
     less memory.

     If there is only one point (if 'x' has length 1), then a nearest
     neighbour distance of 'Inf' is returned. If there are no points
     (if 'x' has length zero) a numeric vector of length zero is
     returned.

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

     Numeric vector of the nearest neighbour distances for each point.

_W_a_r_n_i_n_g_s:

     An infinite value is returned if there is only one point in the
     point 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', 'Gest'

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

        x <- runif(100)
        y <- runif(100)
        d <- nndist(x, y)
        data(cells)
        d <- nndist(cells)

