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How to threshold wavelet coefficients ( keep largest 1/2 of them )?

Posted 12 years ago

I am using Mathematica 9

I got

dwd = DiscreteWaveletTransform[data]

It returns a DiscreteWaveletData object with coefficients ( I assume ).

Now I want to keep only 1/2 largest, to the module , wavelet coefficients from dwd. How to do so?

Is there any way to use WaveletThreshold[] to do that?

Thank you in advance.

POSTED BY: Me Myself
3 Replies
POSTED BY: MinHsuan Peng
Posted 12 years ago

If you want to peek at all the details really returned by DiscreteWaveletTransform then do this:

In[1]:= data = RandomReal[{-1, 1}, {8}];
Normal[DiscreteWaveletTransform[data]]

Out[2]= {{0}->{-0.0640216, 0.201553, 0.566641, 0.44696}, {1}->{-0.0263881, -0.110478, -0.650836, -0.449402},
  {0, 0}->{0.0972497, 0.716724}, {0, 1}->{-0.18779, 0.0846273}, {0, 0, 0}->{0.575566}, {0, 0, 1}->{-0.438034}}

Then on the help page for DiscreteWaveletTransform you can click on Details and Options and guess how to interpret this tree information you are given.

This might even help you see how to check to see whether the processing of the results turned out to be correct.

POSTED BY: Bill Simpson
Posted 12 years ago

Nice, but your answer dosen't seem to be related in any way to my problem. I have checked Details - no insight gained.

POSTED BY: me myself
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