寻找高于阈值的峰值

Question

我正在使用from scipy.signal import find_peaks 。 是否可以找到所有大于指定阈值的峰值。 我不确定你是否能做到这一点。 例如： indices = find_peaks(s_volts, threshold= 0.5*maxPeak)我试图找到大于最大峰值 50% 的所有峰值。

Answer 1

不要认为有一种内置的方法可以做到这一点。 以下是没有 scipy 的方法：

from scipy.signal import find_peaks
import numpy as np
x = np.array([1,2,3,2,1,2,3,2,1,2,3,4,3,2,1,2,3,4,7,4,3,2,1])
peaks_indices = find_peaks(x)[0]
peaks = np.array(list(zip(peaks_indices, x[peaks_indices])))
threshold = 0.5 * max(x[peaks_indices])
filtered_peaks = [(index, value) for index, value in peaks if value > threshold]

# If you just want the indices:
filtered_peaks_indices = [index for index, value in peaks if value > threshold]

# Or just want the values
filtered_peaks_values = [value for index, value in peaks if value > threshold]

# Visualize
from matplotlib import pyplot as plt
plt.plot(range(len(x)), x)
for index in peaks_indices:
     plt.axvline(index)

plt.axhline(threshold)
plt.scatter(filtered_peaks_indices, filtered_peaks_values, s=200)
plt.show()

Answer 2

如果您可以事先定义阈值，则可以使用height参数。 借用@omer-tuchfeld 示例：

from scipy.signal import find_peaks
import numpy as np
from matplotlib import pyplot as plt

x = np.array([1,2,3,2,1,2,3,2,1,2,3,4,3,2,1,2,3,4,7,4,3,2,1])

threshold = 0.5 * max(x)
peaks_indices = find_peaks(x, height=threshold)[0]
peaks_values = x[peaks_indices]

fig = plt.figure()
plt.plot(range(len(x)), x)
for index in peaks_indices:
    plt.axvline(index)

plt.axhline(threshold)
plt.scatter(peaks_indices, peaks_values, s=200)
plt.show()