Lecture 25

Matplotlib

MCS 275 Spring 2023
David Dumas

Lecture 25: Matplotlib

Reminders and announcements:

• Project 3 due 6pm on Friday.
• Homework 10 will be assigned on Thursday or Friday but won't be due until Tuesday after the break.

• Project 4 will allow you to choose a topic, use arbitrary online resources, and collaborate if you want.
• Project 4's focus is on documentation. Half of the grade will be how well you document:
  • Your project topic
  • How I can test your project
  • What sources you used
  • What your individual contribution was

Install

You don't need to install anything if you want to use matplotlib in Google Colab. However, it's hard to work with files in Colab, which be a problem. To install locally:

        python3 -m pip install matplotlib
    

Often paired with:

        python3 -m pip install numpy
        python3 -m pip install notebook
    

See official matplotlib install help.

Plots

Background

MATLAB

MATLAB is a proprietary software package for numerical computation. It has its own language, and is popular in engineering and applied sciences. It was first released in 1984.

It quickly developed a reputation for making it easy to generate nice plots.

Matplotlib

matplotlib is a library for making 2D plots in Python. It was developed starting in 2003 by John Hunter (then a neurobiology postdoc), inspired by the plotting interface of MATLAB.

Today it is the most widely used plotting package for Python, and the Python+numpy+matplotlib "stack" is increasingly popular for applications where MATLAB was once dominant.

Ways to use matplotlib

Matplotlib can be used in several ways:

• In scripts, with output to a file
• In REPL, with plots opening in a GUI
• In IPython notebook, where plots are shown directly in the notebook

Demonstration

Notebook

As with numpy, I'll do most of the intro as a series of coding demos in a notebook.

→ Matplotlib demo notebook ←

While I'll post the notebook after lecture, I suggest using Chapter 4 of VanderPlas as your primary reference because it has detailed explanatory text and sample code notebooks.