quadplot                package:xgobi                R Documentation

_T_e_t_r_a_h_e_d_r_a_l _D_i_s_p_l_a_y _f_o_r _F_o_u_r-_C_a_t_e_g_o_r_y _P_r_o_p_o_r_t_i_o_n_s _u_s_i_n_g _X_G_o_b_i

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

     Four-category proportions are visualized as points inside a
     tetrahedron, using `xgobi'.

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

     quadplot(mat4,
              pointlabs  = rownames(mat4),
              vertexlabs = paste(1:4),
              normalize  = median(abs(c(mat4))) > 1)

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

    mat4: matrix with 4 columns containing the data

pointlabs: character array of labels for rows of data; by default it is
          the row number as a string.

vertexlabs: character array of length 4 of labels for the vertices; by
          default it is the column number as a string.

normalize: logical variable indicating whether or not to force each row
          of data to have unit sum before display, default is false.

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

     The set of all four-category proportions, or, alternatively,
     probability measures on finite probability fields with 4 atomic
     events, is the set of nonnegative 4-vectors whose components sum
     up to 1.  The function `quadplot' uses `xgobi' to represent such
     vectors graphically as points inside a tetrahetron with height 1:
     the four components of the vector are the distances of the point
     to each of the sides of the tetrahetron.  Each vertex of the
     tetrahedron corresponds to the degenerate probability distribution
     in which one of the atomic events has probability 1 and the others
     have probability 0. The labels of these vertices indicate the
     event which has probability 1.

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

     (port to R) Hans Ehrbar ehrbar@econ.utah.edu and Martin Maechler
     (with explicit permission from Jim Ramsay)

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

     `quadplot' was posted by Jim Ramsay ramsay@psych.mcgill.ca to
     S-news on Fri, 21 May 1993 14:03:15 EDT.

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

     data(PaulKAI)
     quadplot(PaulKAI, normalize = TRUE)

