pytutorial/numpy/power_mean

Power and mean

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Questions to David Rotermund

The order is important

You are not allowed to average over the trials before calculating the power. This is the same for calculating the fft power as well as the wavelet power.

import numpy as np
import matplotlib.pyplot as plt

t: np.ndarray = np.linspace(0, 1.0, 10000)
f: float = 10

sinus_a = np.sin(f * t * 2.0 * np.pi)
sinus_b = np.sin(f * t * 2.0 * np.pi + np.pi)

plt.plot(t, sinus_a, label="a")
plt.plot(t, sinus_b, label="b")
plt.plot(t, (sinus_a + sinus_b) / 2.0, "k--", label="(a+b)/2")
plt.legend()
plt.xlabel("t [s]")
plt.show()

![image0.png]

import numpy as np
import matplotlib.pyplot as plt

t: np.ndarray = np.linspace(0, 1.0, 10000)
f: float = 10
n: int = 1000

rng = np.random.default_rng(1)
sinus = np.sin(f * t[:, np.newaxis] * 2.0 * np.pi + 2.0 * np.pi * rng.random((1, n)))
print(sinus.shape)

plt.plot(t, sinus)
plt.plot(t, sinus.mean(axis=-1), "k--")
plt.show()

![image1.png]