artlev1                package:adlift                R Documentation

_a_r_t_l_e_v_1

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

     This function splits the coefficients into levels according to
     increasing quantiles of the removed interval lengths.

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

     artlev1(y, rem)

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

       y: a vector of the removed interval lengths (in the order of
          'removelist'). 

     rem: vector of indices of the removed points (from the output of
          the forward transform). 

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

     The function finds the median of the removed interval lengths, and
     takes all 'pointsin' indices with removed interval lengths at most
     this value as the first artificial level. These indices are now
     not considered in later groups. The cut-off value, q, is now
     increased to the 75th percentile, and the indices at most this
     value are grouped into the second level. The procedure is
     continued with successive percentiles (1+q)/2 until all indices
     are grouped. At each stage, the level size is checked to ensure it
     has at least 10 elements, and if not, the level is taken together
     with the next level (i.e. the present percentile is ignored, and
     increased to the q value).

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

       p: a list of the grouped indices of 'removelist' (in decreasing
          group size) indicating thresholding groups.

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

     Matt Nunes (matt.nunes@bristol.ac.uk), Marina Popa
     (Marina.Popa@bristol.ac.uk)

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

     'denoise',

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

     #create test signal data
     #
     x<-runif(100)
     y<-make.signal2("blocks",x=x)
     #
     #perform forward transform...
     #
     out<-fwtnp(x,y,LocalPred=AdaptNeigh,neighbours=2)
     #
     al<-artlev1(out$lengthsremove,out$removelist)
     #
     #
     # the indices of removelist split into levels:
     al
     #

