I’m trying to recreate the following plot with Numpy and Matplotlib as part of a question, but I’m struggling to get the “random aspect” of the plot:
I’ve already managed to create the two circles and plot them with this code:
import numpy as np
import matplotlib.pyplot as plt
r = [5, 10]
angle = np.linspace(0, 2 * np.pi, 100)
X = [r[0] * np.cos(angle), r[1] * np.cos(angle)]
Y = [r[0] * np.sin(angle), r[1] * np.sin(angle)]
plt.axis('equal');
plt.scatter(X[0], Y[0], c='purple');
plt.scatter(X[1], Y[1], c='yellow');
But I don’t know how to make them get this random scattering, like in the example image. I know I need to use Numpy’s random number generation, but I don’t know how or where to use it, exactly.
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Answer
You might need more than 100 points, so let’s say
t = np.linspace(0, 2 * np.pi, 1000, endpoint=False)
You have the right idea regarding how to build a circle, so add a random radius to each point:
r = np.random.uniform([[4], [9]], [[6], [11]], size=(2, 1000))
This is not necessarily the best way to do it, since the points will be biased towards the center, but it suffices to illustrate the idea.
plt.scatter(r[0] * np.cos(t), r[0] * np.sin(t)) plt.scatter(r[1] * np.cos(t), r[1] * np.sin(t))
On second inspection of your images, you may want to replace np.random.uniform with np.random.normal with a standard deviation of 1.