58 lines
1.7 KiB
Python
58 lines
1.7 KiB
Python
import numpy as np
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from pandas.core.frame import DataFrame
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from scipy.fft import fft, fftfreq
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import pywt
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import sys
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import Handle_emg_data as Handler
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# Normalizes a ndarray of a signal to the scale of int16(32767)
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def normalize_wave(y_values):
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y = np.int16((y_values / y_values.max()) * 32767)
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return y
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# Takes the FFT of a DataFrame object
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def fft_of_df(df:DataFrame):
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y_values = get_xory_from_df('y', df)
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N = y_values.size
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norm = normalize_wave(y_values)
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N_trans = fftfreq(N, 1 / Handler.get_samplerate(df))
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y_f = fft(norm)
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return N_trans, y_f
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# Removes noise with db4 wavelet function
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def wavelet_db4(df:DataFrame):
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y_values = get_xory_from_df('y', df)
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#y_values = normalize_wave(y_values)
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wavelet = pywt.Wavelet('db4')
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cA, cD = pywt.dwt(y_values, wavelet)
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N_trans = np.array(range(int(np.floor((y_values.size + wavelet.dec_len - 1) / 2))))
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return N_trans, cA, cD
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# soft filtering of wavelet trans with the a 1/2 std filter
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def soft_threshold_filter(cA, cD):
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cA_filt = pywt.threshold(cA, np.std(cA)/2)
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cD_filt = pywt.threshold(cD, np.std(cD)/2)
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return cA_filt, cD_filt
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# Inverse dwt for brining denoise signal back to the time domainfi
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def inverse_wavelet(df, cA_filt, cD_filt):
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wavelet = pywt.Wavelet('db4')
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y_new_values = pywt.idwt(cA_filt, cD_filt, wavelet)
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new_len = len(y_new_values)
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old_len = len(get_xory_from_df('y', df))
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if new_len > old_len:
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while new_len > old_len:
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y_new_values = y_new_values[:-1]
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new_len = len(y_new_values)
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old_len = len(get_xory_from_df('y', df))
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return y_new_values
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# NOT FINISHED
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def cepstrum(df:DataFrame):
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N = get_xory_from_df('x', df)
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y = get_xory_from_df('y', df)
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return None
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