How to find peaks in a spectrogram Python [duplicate]

Question

Introduction

I am trying to find peaks in amplitude within a spectrogram I have produced that plots frequency against time and amplitude as the third axis.

I have looked through and attempted to code a solution using scipy.signal.find_peaks_cwt however the official reference guide did not explain what was meant by the widths parameter.

Question:

When finding peaks using scipy.signal.find_peaks_cwt will it return the frequency-time coordinates? If not is there another library or method to use to return the coordinates of local maxima?

What is the widths parameter within scipy.signal.find_peaks_cwt?

As the scipy.signal.find_peaks_cwt deals with arrays why do you still need to plot a spectrogram in order to find local maxima?

Here is the code i have been using to create the spectrogram:

 import numpy as np import matplotlib.pyplot as plt import scipy.io.wavfile from scipy import signal def create_spectrogram(audio): rate, data = scipy.io.wavfile.read(audio) data_1D = data.flatten() plt.specgram(data_1D, NFFT = 64, Fs = 64, noverlap=32) plt.savefig("melody") plt.show() if __name__ == '__main__': audio = "melody.WAV" create_spectrogram(audio)

Here is the outputted Spectrogram:

Links: scipy.signal.find_peaks_cwt reference guide: https://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.signal.find_peaks_cwt.html

Please read how to create a minimal reproducible example and add the missing information to your Post by editing it :) If you haven't read How to Ask yet i recommend to do so :) I highly recommend to follow the 2 guides i linked as the people on SO are more likely to answer questions when the posts follow these guides. What i'm missing in particular is - What have u tried so far? What errors/problems do you face? Do you may have codesnippets that show what you tried so far? — Tobias Theel
– Tobias Theel, Commented Jan 6, 2018 at 17:53
find_peaks_cwt is for 1-D array. If you want to find local peaks in your 2-D spectrogram, please read this: stackoverflow.com/questions/3684484/… — Gerges
– Gerges, Commented Jan 6, 2018 at 22:34

domochevski · Accepted Answer · 2018-01-06 16:02:45Z

Could you please give a bit more information as to how exactly is your data stored in your code? Is it a numpy array, a scipy.signal.spectrogram or simple python lists? A snippet of code would help a lot in trying to help you find a good solution.

For the moment the only "easy" way I would suggest is to have a look at numpy.amax(), choosing wisely the value given to the axis parameter, should get you the maximum you are looking for.

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How to find peaks in a spectrogram Python [duplicate]

Introduction

Question:

Here is the code i have been using to create the spectrogram:

Here is the outputted Spectrogram:

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Collectives™ on Stack Overflow

Introduction

Question:

Here is the code i have been using to create the spectrogram:

Here is the outputted Spectrogram:

1 Answer 1

Comments

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