Code to generate and plot concentric circles

concentric_circles.py

import numpy as np
import matplotlib.pyplot as plt

'''
    Generates points on the boundaries of a circle
    Args:
        center (tuple): The center of the circle
        radius (int): The radius of the circle
        num_points (int): Number of points to generate
        noise_lvl (float): The level of noise to apply to generation
    Returns:
        (numpy.ndarray; shape=(num_points, 2)): The generated points around the defined circle
'''
def circle(center, radius, num_points, noise_lvl):
    h, k = center
    theta = np.random.uniform(0, 2*np.pi, size=num_points)
    x = (h + np.cos(theta) * radius) + np.random.normal(0, noise_lvl, size=num_points)
    y = (k + np.sin(theta) * radius) + np.random.normal(0, noise_lvl, size=num_points)
    
    return np.column_stack((x, y))

'''
    Generates concentric circles with the provided radii
    Args:
        center (tuple): The center of the circles
        radii (list): The radii of the circles
        num_points (int): Number of points to generate for each circle
        noise_lvl (float): The level of additive noise to apply to generation
    Returns:
        points (numpy.ndarray; shape=(num_points, 2)): The generated points that represent the concentric circles
        labels (numpy.ndarray; shape=(num_points, )): The corresponding labels of the generated points
'''
def make_circles(center, radii, num_points, noise_lvl):
    circles = [circle(center, r, num_points, noise_lvl) for r in radii]
    points = np.vstack(circles)
    labels = np.repeat(np.arange(len(radii)), num_points)

    return points, labels


# Plots the concentric circles and colors them with their respective labels
def plot(points, labels, img_name=''):
    fig = plt.figure(figsize=(6, 6))
    plt.axes().set_aspect('equal', 'datalim')
    plt.box(False)
    plt.axis('off')
    plt.scatter(points[:, 0], points[:, 1], c=labels, edgecolors='k', s=30, cmap=plt.cm.twilight)
    plt.show()
    if img_name:
        fig.savefig(f'{img_name}.png')


# Input parameters
center = (0, 0)
radii = np.arange(20) * 10
num_points = 500
noise_lvl = 1

# Generate points
points, labels = make_circles(center, radii, num_points, noise_lvl)

# Plot the circles and save it as an image
plot(points, labels, 'concentric_circles')