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Questions tagged [pywt]

PyWavelets is a free Open Source wavelet transform software for Python programming language.

PyWavelets is a free Open Source wavelet transform software for Python programming language. It is written in Python, Cython and C for a mix of easy and powerful high-level interface and the best performance.

PyWavelets is very easy to start with and use. Just install the package, open the Python interactive shell and type:

import pywt
cA, cD = pywt.dwt([1, 2, 3, 4], 'db1')

Voilà! Computing wavelet transforms never before has been so simple :)

32 questions
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frequency axis in continuous wavelet transform plot (scaleogram) in python

I have an EEG signal that I'm interested in analyzing it in both time and frequency domains. I have already used scipy.signal.spectrogram function, but I think using wavelets can yield better results for feature extraction. I tried running the…
pyigal
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Wavelet plot with Python libraries

I know that SciPy has some signal processing tools for wavelets in scipy.signal.wavelets and a chart can be drawn using Matplotlib, but it seems I can't get it right. I have tried plotting a Daubechies wavelet against a linear space, but it's not…
hyperboreean
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How to calculate energy of an image using Python?

I am trying to calculate the energy of an image. I want to use python. I got one solution from the website but there is a little bit confusing the person who posted the question is telling output of his program is the wrong to compare to Matlab. I…
raviraj
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Pyinstaller ImportError on pywt `_ctw` module

Pywt is not importing _cwt module correctly when the program is compiled with Pyinstaller. I verified that _cwt.py is present in my pywt root (in site-packages on the path) and _cwt.pyd is in the pywt\_extensions dir. I can successfully import…
Manuel J. Diaz
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How to get 2D wavelet by pywt like stft from a wav file?

I am trying to get features from a sound file(.wav)； I have tried stft to get a 2D feature(x is time, y is frequency ) I have tried pywt, but got a 1D array. If I input a 1D (1000,) wav array, I got an array of (500,) How to use pywt to get a 2D…
Simon
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How can i apply continuous wavelet transform for an array of 22 rows and 546304 columns?

I want to apply continuous wavelet transform for an array of 22 rows and 546304 columns (time series signal) to feed the scalograms to CNN. I got error Traceback (most recent call last): File "E:/physionet/wavelet.py", line 144, in…
Eda
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Why does my functions seem to integrate and not differentiate? (pywt.cwt)

I am really confused by the function pywt.cwt, as I've not been able to get it to work. The function seems to integrate instead of differentiating. I would like to work it as the following: Example CWT, but my graph looks like this: My CWT. The idea…
NoTimeLeft
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Creating similar spectrogram in continues wavelet transform compared to discret wavelet transform

Using PyWavelets and Matplotbib.Specgram on a signal gives more detailed plots with pywt.dwt then pywt.cwt. How can I get a pywt.cwt specgram in a similar way? With dwt: import pywt import pywt.data import matplotlib.pyplot as plot from scipy import…
Luc Pingo
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How to draw a haar wavelet plot using pywt?

I'm only in the beginning of learning wavelet transformation, so I have such naive question. I have quite simple scaling function with only two non-zero coefficients: h(0) = h(1) = 1/ sqrt(2) I have calculated the average and difference part on…
Daniel Chepenko
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Memory Error while Using PIL, NUMpy,pywt for satellite images

I am getting a memory error. How to resolve my problem? It seems that satellite images take more memory. Which platform should I use for satellite images? from PIL import Image import numpy as np import pywt im = Image.open("......\B2.TIF")…
Joel
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Making a faster wavelet transform/Appending data faster

I am taking 1-D wavelet transform of data. How can I make this faster? I have 1.4 million samples and 32 features. def apply_wavelet_transform(data): ca,cd=pywt.dwt(data[0,:],'haar') for i in range(1,data.shape[0]): …
Abhishek Bhatia
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Difference between the size of the original image decomposed by wavedec2 and reconstructed by waverec2

I'm using Pywt to work with wavelet transform. I'm doing the decomposition to get the detail coefficients and then the reconstruction by now. I invoke the wavedec2 function with this arguments: X (ndarray 125x125), w = 'sym4', n = 4 coeffs =…
Jorge Rodriguez
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Basic plotting of wavelet analysis output in matplotlib

I am discovering wavelets in practice thanks to the python module pywt. I have browsed some examples of the pywt module usage, but I could not grasp the essential step: I don't know how to display the multidimensionnal output of a wavelet analysis…
Stephane Rolland
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How to Solve Getting nan Entropy in Python?

Based on this paragraph of a paper about brain-computer-interface, I wanna extract time-frequency domain features using discrete wavelet transform and then calculate energy and entropy with the giving equation. So I've chosen pywt in python, and…
Hanie Asemi
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Process finished with exit code -1073741819 (0xC0000005) using PyWavelets on PyCharm

I am get this annoying bug when I try to use the function pywt.cwt on my computer at work (windows64-bit). The code is working fine on my personal mac book. I am getting this message: Process finished with exit code -1073741819 (0xC0000005) and the…
Stravoguine
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