eisera              package:adehabitat              R Documentation

_E_i_g_e_n_a_n_a_l_y_s_i_s _o_f _S_e_l_e_c_t_i_o_n _R_a_t_i_o_s

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

     Performs an eigenanalysis of selection ratios.

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

     eisera(used, available, scannf = TRUE, nf = 2)
     print.esr(x, ...)
     scatter.esr(x, xax = 1, yax = 2, 
                 csub = 1, possub = "bottomleft", ...)

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

    used: a data frame containing the *number* of relocations of each
          animal (rows) in each habitat type (columns) 

available: a data frame containing the *proportion* of availability of
          each habitat type (columns) to each animal (rows)

  scannf: logical.  Whether the eigenvalues bar plot should be
          displayed

      nf: if 'scannf = FALSE', an integer indicating the number of kept
          axes

       x: an object of class 'esr'

     xax: the column number for the x-axis

     yax: the column number for the y-axis

    csub: a character size for the legend, used with  'par("cex")*csub'

  possub: a string of characters indicating the sub-title  position
          ("topleft", "topright", "bottomleft",  "bottomright")

     ...: further arguments passed to or from other methods

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

     The eigenanalysis of selection ratios has been developped to
     explore habitat selection by animals monitored using
     radio-tracking, when habitat is defined by several categories
     (e.g. several vegetation types, see Calenge and Dufour 2006).

     This analysis can be used for both designs II (same availability
     for all animals, e.g. selection of the home range within the study
     area) and designs III (different availability, e.g. selection of
     the sites within the home range).  In the latter case, when some
     available proportions are equal to zero, the selection ratios are
     replaced by their expectation under random habitat use, following
     the recommendations of Calenge and Dufour (2006).

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

     An object of class 'esr'

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

     Clment Calenge calenge@biomserv.univ-lyon1.fr

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

     Calenge, C. and Dufour, A.B. (2006) Eigenanalysis of selection
     ratios from animal radio-tracking data. _Ecology_. *in press*.

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

     'widesII' for further information about the selection ratios,
     'compana' for compositional analysis.

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

     ###########################################################
     ###########################################################
     ###
     ###  Example given in Calenge and Dufour 2006 (design II)

     data(squirrel)

     ## computation of the number of relocations in each habitat type
     ## from the data given by Aebischer et al. (1993).
     ## squirrel$locs give the percentage of relocations in each habitat
     ## type, and Aebischer et al. (1993) indicate that there are 30
     ## relocations per animal.
     ## We therefore compute the number of relocations in each habitat type
     ## using:
     us <- round(30 * squirrel$locs / 100)

     ## Habitat availability 
     av <- squirrel$studyarea

     ## Eigenanalysis of selection ratios
     ii <- eisera(us, av, scannf = FALSE)

     scatter(ii, grid = FALSE, clab = 0.7)

     ###########################################################
     ###########################################################
     ###
     ###  Example of design III

     iii <- eisera(us, squirrel$mcp, scannf = FALSE)
     scatter(iii, grid = FALSE, clab = 0.7)

