

accessD(wavethresh)                          R Documentation

_G_e_t _w_a_v_e_l_e_t _e_x_p_a_n_s_i_o_n _c_o_e_f_f_i_c_i_e_n_t_s _f_r_o_m _w_a_v_e_l_e_t _s_t_r_u_c_t_u_r_e_.

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

     The coefficients from a wavelet expansion in a wavelet
     decomposition structure (returned from wd or wr) are
     packed into a single vector in that structure.  This
     function extracts the coefficients corresponding to a
     particular resolution level.

_U_s_a_g_e_:

     accessD(wd.obj, level, boundary=FALSE)

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

  wd.obj: Wavelet decomposition structure from which you
          wish to extract the expansion coefficients.

   level: The level that you wish to extract. If the "origi-
          nal" data has 2^m data points then there are m
          possible levels that you could want to access,
          indexed by 0,1,...{},(m-1).

boundary: If this argument is TRUE then all of the boundary
          correction values will be returned as well (note:
          the length of the returned vector may not be a
          power of 2). If boundary is false, then just the
          coefficients will be returned. If the decomposi-
          tion (or reconstruction) was done using periodic
          boundary handling then this option has no effect.

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

     The wd (wr) function produces a wavelet decomposition
     (reconstruction) structure.

     The need for this function is a consequence of the
     pyramidal structure of Mallat's algorithm and the mem-
     ory efficiency gain achieved by storing the pyramid as
     a linear vector.  AccessD obtains information about
     where the coefficients appear from the fl.dbase compo-
     nent of wd.obj, in particular the array
     fl.dbase$first.last.d which gives a complete specifica-
     tion of index numbers and offsets for `wd.obj$D'.

     Note that this function and accessC only work on
     objects of class `wd'. Also, you have to use putD to
     put wavelet coefficients into a wd object.

_V_a_l_u_e_:

     A vector of the extracted coefficients.

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

     `wr' and `wd' for background information; `accessC',
     `filter.select', `threshold', `putC', `putD'.

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

     example(wd)

     ## Get the 3rd level coefficients of a decomposition
     accessD(wds, level=3)

     ## Do a qqnorm plot to assess the normality of some coefficients
     qqnorm(accessD(wds, level=8))

