rndtaxa                package:labdsv                R Documentation

_R_a_n_d_o_m_i_z_e _a _T_a_x_a _D_a_t_a _F_r_a_m_e

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

     Permutes a vegetation (or other) data frame to establish a basis
     for null model tests in vegetation ecology.

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

     rndtaxa(taxa,replace=FALSE,species=FALSE,plots=FALSE)

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

    taxa: the vegetation (or other taxon) data.frame, samples as rows,
          species as columns

 replace: a switch for permuting (if FALSE) or boostrapping (if TRUE)

 species: a switch to control randomizing by species (if TRUE),
          maintaining species occurrence distributions

   plots: a switch to control randomizing by samples (if TRUE),  
          maintaining plot-level species richness

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

     Permutes or bootstraps a vegetation data frame for input to 
     'dist', 'vegdist', 'dsvdis', or other routines.  Can randomize by
     columns (species=TRUE), samples  (plots=TRUE), or fully (neither
     species nor plots = TRUE).

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

     a data.frame with samples as rows and species as columns of the
     same dimensions as entered.

_N_o_t_e:

     Randomizing vegetation often leads to unrealistic data
     distributions, but this function attempts to preserve either
     species occurrence distributions or plot-level species richness. 
     It is probably worth examining the output of this function with
     'abuocc' to see its characteristics before engaging in extensive
     analysis.

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

     David W. Roberts droberts@montana.edu <URL:
     http://ecology.msu.montana.edu/droberts>

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

     <URL: http://ecology.msu.montana.edu/labdsv/R>

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

         data(bryceveg) # returns a vegetation data.frame called bryceveg
         test <- rndtaxa(bryceveg,species=TRUE) # preserves species abundance 
                 # distribution
         test2 <- rndtaxa(bryceveg,plots=TRUE) # preserves plot-level species richness

