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Questions tagged [pywavelets]

55 questions
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Why is Wavelet Denoising producing identical results regardless of threshold level?

I'm trying to denoise financial time series data (second by second). I have a very long time series, but I've been working with 100,000 observations just to test how well the wavelet denoising (haar) works. It doesn't. No matter what I do, the…
TheMathBoi
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Python/PyWavelet implementation of Shannon Entropy optimized WaveletPacket Tiling

I need to run a Shannon (or any such metric) Entropy minimization for a wavelet packet tree, but I'm having problems sussing out the algorithm. Sometimes this is referred to as optimizing the tiles in frequency-space. I can follow solve the problem…
NRG
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Dtype to nparray.dtype

My intention is to use pywavelet on a tensor in tensorflow, with the sentence pywt.dwt(input,'db1') The error was Cannot convert DType to numpy.dtype Input is a Tensor("Reshape_18:0", shape=(?, 28, 28, 1), dtype=float32) from MNIST dataset. I try…
Mari Ar
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Multilevel Wavelet Decomposition not working

I am trying to decompose the given wave by using a db4 wavelet and 5 level decomposition. Here is the code for the same : coeffs = pywt.wavedec(yourResultA,'db4',level = 5) However the editor is giving me the following error: Level value of 5 is…
Rohan Akut
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Confusing artifacts in PyWavelet complex-Morlet analysis of 1-kHz signal

I have some artifacts in a PyWavelets transform that are really confusing me. I'm using version 0.5.2. Can someone explain what is happening here? I start by creating a 1-kHz signal, and then I attempt to analyze this signal with a complex Morlet…
Adam Smith
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How to define a custom Ricker wavelet using pywavelets?

I have been struggling with defining a custom wavelet using pywavelets. I would like to perform a DWT using the ricker wavelet. However, the ricker wavelet does not seem to be part of the in-built wavelet family provided by pywavelets. The official…
Akshay S
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Lifting schemes implementation in python for Haar DWT?

I am trying to code Haar DWT based steganography. Coefficients of subbands are coming in float64. In order to embed secret in pixels, I need subband as integers. Matlab provides a lifting schemes to convert subbands to integers. Does any python…
Himani Agrawal
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Python Array Output for Loops

I want to run a loop over every 33 observations and perform a discrete wavelet transform using PyWavelets on that subset of data. I've searched far and wide for a similar issue using PyWavelets, but can't find anything. I've looked into looping…
user2573355
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How to limit the number of coefficients to use in reconstructing a 1D signal using wavelet decomposition in python

I am new in the area of using wavelet decomposition. And I am trying to decompose and reconstruct (with very few coefficients) a 1D data in python (using pywt). From this documentation I wrote the code below which reconstructs the data with 512…
Kela
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Clarifications about pywavelet return values

I'm trying out PyWavelets and following this example. import pywt x = [3, 7, 1, 1, -2, 5, 4, 6] cA, cD = pywt.dwt(x, 'db2') Just to confirm, is cA the scaling and cD the time delay? Any way to change shift/scale step (a and b parameters from…
Bobo
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