entrupd (Wavelet Toolbox)

Entropy update (wavelet packet).

NDATA = entrupd(TREE,DATA,ENT)
NDATA = entrupd(TREE,DATA,ENT,PAR)

Description

entrupd is a one- or two-dimensional wavelet packets utility.

NDATA = entrupd(TREE,DATA,ENT) or
NDATA = entrupd(TREE,DATA,ENT,PAR) returns for a given wavelet packet decomposition structure [TREE,DATA] (see maketree), the updated data structure NDATA corresponding to entropy function ENT with optional parameter PAR (see wentropy).

[TREE,NDATA] is the resulting decomposition structure.

Examples

% Load signal. 
    load noisdopp; x = noisdopp;

% Decompose x at depth 2 with db1 wavelet packets 
% using shannon entropy. 
    [t,d] = wpdec(x,2,'db1','shannon');

% Read entropy of all the nodes. 
    nodes = allnodes(t);
    ent = wdatamgr('read_ent',d,nodes)

ent =
    1.0e+04 *
    -5.8615 -6.8204 -0.0350 -7.7901 -0.0497 -0.0205 -0.0138

% Update nodes entropy without changing tree 
% and data structures. 
    d = entrupd(t,d,'threshold',0.5); 
    nent = wdatamgr('read_ent',d,nodes)


nent =
    937 488 320 241 175 170 163