mapasp                  package:sp                  R Documentation

_C_a_l_c_u_l_a_t_e _a_s_p_e_c_t _r_a_t_i_o _f_o_r _p_l_o_t_t_i_n_g _g_e_o_g_r_a_p_h_i_c _m_a_p_s

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

     Calculate aspect ratio for plotting geographic maps

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

      
     mapasp(data, xlim, ylim)

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

    data: object of class or extending 'Spatial'

    xlim: the xlim argument passed (or derived from bounding box) 

    ylim: the ylim argument passed (or derived from bounding box) 

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

     'mapasp' is used for the aspect argument in lattice plots and
     spplot; 

     let x = dy/dx, with dy and dx the y- and x-size of the map.

     let s = 1/cos((My * pi)/180) with My the y coordinate of the
     middle of the map (the mean of ylim)

     for latlong (longlat) data, 'mapasp' returns s * x. for other
     data, mapasp returns "iso".

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

     levelplot in package 'lattice'

