affine               package:spatstat               R Documentation

_A_p_p_l_y _A_f_f_i_n_e _T_r_a_n_s_f_o_r_m_a_t_i_o_n

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

     Applies any affine transformation of the plane (linear
     transformation plus vector shift) to a plane geometrical object,
     such as a point pattern or a window.

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

      affine(X, mat=diag(c(1,1)), vec=c(0,0))

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

       X: Any suitable dataset representing a two-dimensional object,
          such as a point pattern (object of class `"ppp"'), or a
          window (object of class `"owin"').

     mat: Matrix representing a linear transformation.

     vec: Vector of length 2 representing a translation.

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

     This is generic. Methods are provided for point patterns
     (`affine.ppp') and windows (`affine.owin').

     First the linear transformation represented by `mat' is applied
     (multiplying on the left by `mat'), and then the result is
     translated by the vector `vec'.

     The argument `mat' must be a nonsingular 2 * 2 matrix.

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

     Another object of the same type, representing the result of
     applying the affine transformation.

_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:

     `affine.ppp', `affine.owin', `rotate', `shift'

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

       library(spatstat)
       data(cells)
       # shear transformation
       X <- affine(cells, matrix(c(1,0,0.6,1),ncol=2))

       plot(X)
       # rescale y coordinates by factor 1.3
       plot(affine(cells, diag(c(1,1.3))))


