idt               package:compositions               R Documentation

_I_s_o_m_e_t_r_i_c _d_e_f_a_u_l_t _t_r_a_n_s_f_o_r_m

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

     Compute the isometric default transform of a vector (or dataset)
     of compositions or amounts in the selected class.

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

               idt(x)
               ## Default S3 method:
               idt( x )
               ## S3 method for class 'acomp':
               idt( x )
               ## S3 method for class 'rcomp':
               idt( x )
               ## S3 method for class 'aplus':
               idt( x )
               ## S3 method for class 'rplus':
               idt( x )
               ## S3 method for class 'rmult':
               idt( x )
               ## S3 method for class 'factor':
               idt( x )
               

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

       x: a classed amount or composition, to be transformed with its
          isometric default transform

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

     The general idea of this package is to analyse the same data with
     different geometric concepts, in a fashion as similar as possible.
     For each of the four concepts there exists an isometric transform
     expressing the geometry in a full-rank euclidean vector space.
     Such a transformation is computed by 'idt'. For 'acomp' the
     transform is 'ilr', for 'rcomp' it is 'ipt', for  'aplus' it is
     'ilt', and for 'rplus' it is 'iit'. Keep in mind that the
     transform does not keep the variable names, since there is no
     guaranteed  one-to-one relation between the original parts and
     each transformed variable.

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

     A corresponding matrix of row-vectors containing the transforms.

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

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

     'cdt', 'ilr', 'ipt', 'ilt', 'iit'

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

     ## Not run: 
     # the idt is defined by
     idt         <- function(x) UseMethod("idt",x)
     idt.default <- function(x) x
     idt.acomp   <- function(x) ilr(x) 
     idt.rcomp   <- function(x) ipt(x) 
     idt.aplus   <- ilt 
     idt.rplus   <- iit 
     ## End(Not run)
     idt(acomp(1:5))
     idt(rcomp(1:5))

