如何使用matplotlib将波形绘制为曲线？

Question

我写了这段代码：

def plotWaveforms(audioFile1, audioFile2, imageFile, startSegment=30, endSegment=35, amp1=0.5, amp2=0.5):
    # Load audio files
    y1, sr1 = librosa.load(audioFile1, sr=None, offset=startSegment, duration=endSegment - startSegment)
    y2, sr2 = librosa.load(audioFile2, sr=None, offset=startSegment, duration=endSegment - startSegment)
    
    # Normalize and adjust the amplitude of the audio signals
    y1 = normalize_audio(y1, amp1)
    y2 = normalize_audio(y2, amp2)
    
    # Create a figure with a black background
    plt.figure(figsize=(16, 1), facecolor='black')
    
    # Plot the second audio file as a filled waveform
    plt.fill_between(np.linspace(0, len(y2) / sr2, len(y2)), y2, color='green', alpha=1)

    # Plot the first audio file as a filled waveform
    plt.fill_between(np.linspace(0, len(y1) / sr1, len(y1)), y1, color='blue', alpha=0.5)
    
    # Remove axes, labels, and title for a clean look
    plt.axis('off')
    
    # Save the figure with a specific resolution
    plt.savefig(imageFile, format='png', dpi=300, bbox_inches='tight', pad_inches=0)
    plt.close()

产生这个：

但我试图使用每个点的峰值或定期间隔绘制一条填充曲线，如下所示：

我该怎么做？

Answer 1

您可以使用

argrelextrema

中的

scipy.signal

来获取最小值或最大值的索引。这是一个小教程：

import pandas as pd
%matplotlib notebook
import matplotlib.pyplot as plt
import numpy as np
from scipy.signal import argrelextrema
fs = 44000  # 44 kHz
duration = 10  # seconds
N = int(fs * duration) # get number of samples
t = np.linspace(0, duration, N) # generate time vector
f = 1000  # 1 kHz
a = np.log(0.01) / duration # decay
y = np.exp(a * t) * np.sin(2 * np.pi * f * t) # generate signal
y = pd.Series(y, index=t) # as a series
minimaIdx = argrelextrema(y.values, np.less)[0] # get index of minima
maximaIdx = argrelextrema(y.values, np.greater)[0] # get index of maxima
minima = y.iloc[minimaIdx] # get minima
maxima = y.iloc[maximaIdx] # get maxima
plt.plot(y, label='Dampened Sine Function') # plot the signal
plt.plot(minima,  "-o", color='red', label='Local Minima') # the manima
plt.plot(maxima, "-s", color='green', label='Local Maxima') # and the maxima
# add decorations...
plt.xlabel('Time (s)')
plt.ylabel('Amplitude')
plt.title('Dampened Sine Function with Local Extrema')
plt.legend()
plt.grid()

这就是它的样子：

要填写最大值和 0 之间的值，您可以使用这个简单的插图：

plt.figure()
plt.fill_between(maxima.index, 0, maxima.values, color='lightblue', label='Area between 0 and Maxima')
plt.xlabel('Time (s)')
plt.ylabel('Amplitude')
plt.title('Area Under Maxima')
plt.legend()
plt.grid()

你会得到这个：

我之前已经用音频信号做过这个，它应该工作得很好。希望这有帮助！