const                 package:labdsv                 R Documentation

_C_o_n_s_t_a_n_c_y _T_a_b_l_e

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

     For a classified set of vegetation samples, lists for each species
     the fraction of samples in each class the species occurs in.

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

     const(taxa, clustering, minval = 0, digits = 2, spcord = NULL)

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

    taxa: a data.frame of species abundances with samples as rows and
          species as columns

clustering: a vector of (integer) cluster memberships, or an object of
          class 'clustering', class 'partana', or class 'partition'

  minval: the minimum constancy a species must have in at least one
          class to be included in the output

  digits: the number of digits to report in the table

  spcord: a vector of integers to specify the order in which species
          should be listed in the table

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

     Produces a table with species as rows, and species constancy in
     clusters as columns.

     The 'clustering' vector represents a classification of the samples
     that the table summarizes.  It may result from a cluster analysis,
     partitioning an ordination, subjective partitioning of a
     vegetation table, or other source.

     The 'minval' argument is used to emphasize the dominant species
     and suppress the rare species.  Vegetation tables are often very
     sparse, and this argument simplifies making them more compact.

     The 'digits' argument limits the reported precision of the
     calculations. Generally, relatively low precision is adequate and
     perhaps more realistic.

     The 'spcord' argument specifies the order species are listed in a
     table. You can use the reverse of the number of occurrences to get
     dominant species at the top to rarer at the bottom, use fidelity
     values for the ordered clusters, or possibly the order of species
     centroids in an ordination.

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

     a data.frame with species as rows, classes as columns, with
     fraction of occurrence of species in classes.

_N_o_t_e:

     Constancy tables are often used in vegetation classification to
     calculate or present characteristic species for specific classes
     or types. 'const' may be combined with 'importance' and 'vegtab'
     to achieve a vegetation table-oriented analysis.

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

     David W. Roberts droberts@montana.edu

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

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

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

     'importance', 'vegtab', 'vegemite'

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

     data(bryceveg) # returns a data.frame called bryceveg
     class <- sample(1:10,nrow(bryceveg),replace=TRUE)
     const(bryceveg,class,minval=0.25)

