Drawing Ellipses with Python Matplotlib

Introduction

This lab demonstrates how to use Python Matplotlib to draw ellipses. The lab covers two examples:

• Drawing individual ellipses
• Drawing ellipses with different angles

  You can open the ellipse-demo.ipynb in WebIDE to start the exercises. Learn how to use Jupyter Notebooks in VS Code.
  
  Labby cannot automatically verify the answers because it cannot access the notebook.

Importing Required Libraries

First, we need to import the required libraries. We will use numpy to generate random data, and matplotlib.pyplot and matplotlib.patches to draw the ellipses.

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.patches import Ellipse

Drawing Individual Ellipses

In this example, we will draw many ellipses with random sizes, positions, and colors. Each ellipse will be an instance of the Ellipse class.

## Fixing random state for reproducibility
np.random.seed(19680801)

## Number of ellipses to draw
NUM = 250

## Generate the ellipses
ells = [Ellipse(xy=np.random.rand(2) * 10,
                width=np.random.rand(), height=np.random.rand(),
                angle=np.random.rand() * 360)
        for i in range(NUM)]

## Create the plot and set the aspect ratio to 'equal'
fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})

## Add each ellipse to the plot
for e in ells:
    ax.add_artist(e)
    e.set_clip_box(ax.bbox)
    e.set_alpha(np.random.rand())
    e.set_facecolor(np.random.rand(3))

## Set the x and y limits of the plot
ax.set_xlim(0, 10)
ax.set_ylim(0, 10)

## Show the plot
plt.show()

Drawing Ellipses with Different Angles

In this example, we will draw many ellipses with different angles. We will use a loop to create an Ellipse instance for each angle we want to draw.

## Define the angle step and the range of angles to draw
angle_step = 45  ## degrees
angles = np.arange(0, 180, angle_step)

## Create the plot and set the aspect ratio to 'equal'
fig, ax = plt.subplots(subplot_kw={'aspect': 'equal'})

## Loop over the angles and draw an ellipse for each angle
for angle in angles:
    ellipse = Ellipse((0, 0), 4, 2, angle=angle, alpha=0.1)
    ax.add_artist(ellipse)

## Set the x and y limits of the plot
ax.set_xlim(-2.2, 2.2)
ax.set_ylim(-2.2, 2.2)

## Show the plot
plt.show()

Summary

In this lab, we have learned how to use Python Matplotlib to draw ellipses. We have covered two examples: drawing individual ellipses and drawing ellipses with different angles. By following the steps in this lab, you should be able to draw ellipses in your own Python projects using Matplotlib.