Find all peaks amplitude lies above 0 Using Scipy (original) (raw)

Last Updated : 23 Jul, 2025

Prerequisites: Matplotlib, Scipy

In this article, we will see how to find all 'x' point above 0 with the help of find_peaks( ) function, that takes a 1-D array and finds all local maxima by a simple comparison of neighboring values.

Approach:

• Import required module.
• Find peaks inside a signal based on find_peaks() properties.
• Label the graph.
• Display Graph.

Step 1: Import all libraries.

Python3 `

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

`

Step 2: electrocardiogram(): The returned signal is a 5-minute-long electrocardiogram (ECG), a medical recording of the heart’s electrical activity, sampled at 360 Hz.

Syntax:

scipy.signal.find_peaks(x, height=None)

Parameter:

• x: A signal with peaks.
• height: Required height of peaks. Either a number, None,

Return:

peaks: Indices of peaks in x that satisfy all given conditions.
peak_heights: If the height is given, the height of each peak is x.

Python3 `

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

t = np.linspace(0, 1, 500, endpoint=False) sig = np.sin(2 * np.pi * t) x= signal.square(2 * np.pi * 30 * t, duty=(sig + 1)/2) peak, _ = find_peaks(x, height=0)

`

Below is the full Implementation:

Python3 `

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

t = np.linspace(0, 1, 500, endpoint=False) sig = np.sin(2 * np.pi * t) x= signal.square(2 * np.pi * 30 * t, duty=(sig + 1)/2) peak, _ = find_peaks(x, height=0)

plt.plot(x) plt.title("Find peaks inside a signal - Geeksforgeeks") plt.plot(peak, x[peak], "x", color = 'r') plt.plot(np.zeros_like(x), "--", color="black") plt.show()

`

Output: