Creating a Color Demo Chart

Introduction

In this lab, we will learn how to create a color demo chart using Python's Matplotlib library. Matplotlib provides a variety of ways to specify colors, which can be used in charts, graphs, and other visualizations. We will explore these different ways of specifying colors and use them to create a chart showing voltage vs. time.

VM Tips

After the VM startup is done, click the top left corner to switch to the Notebook tab to access Jupyter Notebook for practice.

Sometimes, you may need to wait a few seconds for Jupyter Notebook to finish loading. The validation of operations cannot be automated because of limitations in Jupyter Notebook.

If you face issues during learning, feel free to ask Labby. Provide feedback after the session, and we will promptly resolve the problem for you.

Import Required Libraries

Before we begin, we need to import the Matplotlib and NumPy libraries:

import matplotlib.pyplot as plt
import numpy as np

Define Data

Next, we need to define the data that we will use for our chart. We will create a sine wave with 201 data points:

t = np.linspace(0.0, 2.0, 201)
s = np.sin(2 * np.pi * t)

Specify Colors

Matplotlib provides several ways to specify colors, including:

1. An RGB or RGBA tuple of float values in [0, 1].
2. A hex RGB or RGBA string.
3. A shorthand hex RGB or RGBA string.
4. A string representation of a float value in [0, 1] inclusive for gray level.
5. A single letter string, i.e. one of {'b', 'g', 'r', 'c', 'm', 'y', 'k', 'w'}.
6. A X11/CSS4 ("html") color name.
7. A name from the xkcd color survey, prefixed with 'xkcd:'.
8. A "Cn" color spec, i.e. 'C' followed by a number.
9. One of {'tab:blue', 'tab:orange', 'tab:green', 'tab:red', 'tab:purple', 'tab:brown', 'tab:pink', 'tab:gray', 'tab:olive', 'tab:cyan'}.

We will use several of these methods to specify the colors for our chart.

Create Chart

Now we can create our chart using the data and colors that we have specified:

fig, ax = plt.subplots(facecolor=(.18, .31, .31))
ax.set_facecolor('#eafff5')
ax.set_title('Voltage vs. time chart', color='0.7')
ax.set_xlabel('Time [s]', color='c')
ax.set_ylabel('Voltage [mV]', color='peachpuff')
ax.plot(t, s, 'xkcd:crimson')
ax.plot(t, .7*s, color='C4', linestyle='--')
ax.tick_params(labelcolor='tab:orange')

Display Chart

Finally, we can display our chart using the following command:

plt.show()

Summary

In this lab, we learned how to create a color demo chart using Python's Matplotlib library. We explored several ways to specify colors and used them to create a chart showing voltage vs. time. We hope that this tutorial has been helpful in learning how to use Matplotlib to create charts and visualizations.