Fhat                 package:splancs                 R Documentation

_F _n_e_a_r_e_s_t _n_e_i_g_h_b_o_u_r _d_i_s_t_r_i_b_u_t_i_o_n _f_u_n_c_t_i_o_n

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

     Calculates an estimate of the F nearest neighbour distribution
     function

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

     Fhat(pts1,pts2,s)

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

    pts1: A points data set 

    pts2: A points data set 

       s: A vector of distances at which to evaluate Fhat 

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

     A vector of the same length as `s', containing the value of Fhat
     at the  distances in `s'.

_M_E_T_H_O_D:

     The function `Fhat(pts1,pts2,s)' is defined as the proportion of
     members of a point set `pts2' for which the distance to the
     nearest member of another points set `pts1' is less than or equal
     to `s'.

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

     Rowlingson, B. and Diggle, P. 1993 Splancs: spatial point pattern
     analysis code in S-Plus.  Computers and Geosciences, 19, 627-655;
     the original sources can be accessed at: <URL:
     http://www.maths.lancs.ac.uk/~rowlings/Splancs/>. See also Bivand,
     R. and Gebhardt, A. 2000 Implementing functions for spatial
     statistical analysis using the R language. Journal of Geographical
     Systems, 2, 307-317.

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

     `nndistF',`Fzero'

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

     data(uganda)
     plot(seq(20, 500, 20), Fhat(as.points(uganda), 
     as.points(csr(uganda$poly, length(uganda$x))), seq(20, 500, 20)), 
     type="l", xlab="distance", ylab="Estimated F")
     plot(Ghat(as.points(uganda), seq(20, 500, 20)), Fhat(as.points(uganda), 
     as.points(csr(uganda$poly, length(uganda$x))), seq(20, 500, 20)), 
     type="l", xlab="Estimated G", ylab="Estimated F")
     lines(c(0,1),c(0,1),lty=2)

