read

Read values of WPTREE

Syntax

value = read(T,propname,propparam)

Description

value = read(T,propname,propparam) returns the value of the wavelet packet tree T property specified by propname. propparam is an optional parameter depending on the value of propname.

You can specify one or more properties in any order. propname-propparam arguments must appear after other arguments. For example, [value1,value2,value3,value4] = read(T,propname1,propname2,propname3,propparam3,propname4,propparam4).

Examples

Wavelet Packet Tree Properties

Create a wavelet packet tree.

x = rand(1,512);
t = wpdec(x,3,"db3");
t = wpjoin(t,[4;5]);

Display the tree.

plot(t)

Obtain the size of the data at every node in ascending node index order.

sAll = read(t,"sizes")

sAll = 11×2

     1   512
     1   258
     1   258
     1   131
     1   131
     1   131
     1   131
     1    68
     1    68
     1    68
      ⋮

Obtain the size of the data at nodes of indices 0, 4 and 5.

sNod = read(t,"sizes",[0,4,5])

sNod = 3×2

     1   512
     1   131
     1   131

Obtain the entropy of all the nodes.

eAll = read(t,"ent")

eAll = 11×1

  116.3597
   45.9147
   39.1646
  -30.2074
   17.6607
   20.8560
   18.8364
 -114.8913
   11.4664
    9.2578
      ⋮

Obtain the entropy at nodes of indices 0, 4 and 5.

eNod = read(t,"ent",[0,4,5])

eNod = 3×1

  116.3597
   17.6607
   20.8560

Obtain the wavelet filters and wavelet coefficients.

[loD,hiD,loR,hiR] = read(t,"wfilters");
[loD1,loR1,hiD1,hiR1] = read(t,"wfilters","l","wfilters","h");
[max(abs(loD-loD1)) max(abs(hiD-hiD1)) ...
    max(abs(loR-loR1)) max(abs(hiR-hiR1))]

ans = 1×4

     0     0     0     0

Obtain the wavelet coefficients at all nodes.

dAll = read(t,"data");

Obtain the wavelet coefficients at nodes of indices 4 and 5.

dNod = read(t,"data",[4;5]);
[ent,cfs4,cfs5]  = read(t,"ent","cfs",4,"cfs",5);
[max(abs(dNod{1}-cfs4)) max(abs(dNod{2}-cfs5))]

ans = 1×2

     0     0

Plot the coefficients at node index 4.

plot(cfs4)
title("Node 4 Wavelet Coefficients")

Input Arguments

T — Wavelet packet tree

WPTREE object

Wavelet packet tree, specified as a WPTREE object.

propname — Wavelet packet tree property name

character vector | string scalar

Wavelet packet tree property name, specified as one of the following:

Property Name (propname)	Property Parameter (propparam)
"ent", "ento" or "sizes" (see wptree)	Without propparam or with propparam = Vector of node indices, value contains the entropy (or optimal entropy, or size) of the tree nodes in ascending node index order.
"cfs"	With propparam = One terminal node index. value = read(T,"cfs",NODE) is equivalent to value = read(T,"data",NODE) and returns the coefficients of the terminal node NODE.
"entName", "entPar", "wavName" (see wptree) or "allcfs"	Without propparam. value = read(T,"allcfs") is equivalent to value = read(T,"data"). value contains the desired information in ascending node index order of the tree nodes.
"wfilters" (see wfilters)	Without propparam or with propparam = "d","r","l","h".
"data"	Without propparam or with propparam = One terminal node index or propparam = Column vector of terminal node indices. In this last case, value is a cell array. Without propparam, value contains the coefficients of the tree nodes in ascending node index order.

Example: [value1,value2,value3,value4] = read(T,"wavName","allcfs","cfs",4,"wfilters","h")

propparam — Property parameter

integer | vector of integers

Parameter associated with the property propname, specified as an integer or vector of integers.

Version History

Introduced before R2006a