ben741

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace (0, 50, 1000)
y = 0.75 * np.sin(x)

peaks = np.where((y[1:-1] > y[0:-2]) * (y[1:-1] > y[2:]))[0] + 1
dips = np.where((y[1:-1] < y[0:-2]) * (y[1:-1] < y[2:]))[0] + 1

# The above makes a list of all indices where the value of y[i] is greater than both of its neighbours