steppe                 package:ade4                 R Documentation

_T_r_a_n_s_e_c_t _i_n _t_h_e _V_e_g_e_t_a_t_i_o_n

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

     This data set gives the presence-absence of 37 species on 515
     sites.

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

     data(steppe)

_F_o_r_m_a_t:

     'steppe' is a list of 2 components.

     _t_a_b is a data frame with 512 rows (sites) and 37 variables
          (species) in presence-absence.

     _e_s_p._n_a_m_e_s is a vector of the species names.

_S_o_u_r_c_e:

     Estve, J. (1978) Les mthodes d'ordination : lments pour une
     discussion. in J. M. Legay and R. Tomassone, editors.  _Biomtrie
     et Ecologie_, Socit Franaise de Biomtrie, Paris, 223-250.

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

     par(mfrow = c(3,1))
     data(steppe)
     w1 <- col(as.matrix(steppe$tab[,1:15]))
     w1 <- as.numeric(w1[steppe$tab[,1:15] > 0])
     w2 <- row(as.matrix(steppe$tab[,1:15]))
     w2 <- as.numeric(w2[steppe$tab[,1:15] > 0])
     plot(w2, w1, pch = 20)
     plot(dudi.pca(steppe$tab, scan = FALSE, scale = FALSE)$li[,1],
         pch = 20, ylab = "PCA", xlab = "", type = "b")
     plot(dudi.coa(steppe$tab, scan = FALSE)$li[,1], pch = 20, 
         ylab = "COA", xlab = "", type = "b")
     par(mfrow = c(1,1))

