Lecture 19 - jupyter notebooks

Things look a little different right now

We're going to start by introducing a new programming environment: Jupyter Notebooks

Link to notes on Jupyter Notebooks

There are a few things that are really nice about Jupyter Notebooks:

• I can have text cells (like this one)
• I can also have code cells (like the following one)

# this is a code cell
# write python code as normal

print("hello world!")
x = 10
print(x ** 7)

hello world!
10000000

Awesome things about notebooks

• They are convenient ways to visualize data and graphs in the context of code
• Cells can be used to help indicate what pieces of the code goes together sematically
• Easy to mix text (notes) together with code

import matplotlib.pyplot as plt


def make_plot(title):
    plt.plot([1, 2, 3, 4], [2, 3, 0, 5])
    plt.title(title)
    plt.show()
    
make_plot("first plot")

make_plot("second plot from other cell")

Confusing things about notebooks

• They do not enforce top-to-bottom code execution
  • I can run cells in any order I want to
• The kernel (your program's memory) continuously runs
  • This means that when you run a cell, any variables and functions defined are accessible in cells that you run in the future
• they make keeping track of scope complex!

# scope and continuous kernel examples
x = 10
print(x)

10

y = 100
print("y's value:", y)

y's value: 100

print(y)

100

Prof. Felix's Notebook recommendations

• If you use them, always double check your work by doing "Kernel" > "Restart & Run All"
• You can always also save your notebook as a .py file and run it "normally" if you'd like to
  • "File" > "Download As" > "Python (.py)"
• If you save a notebook as .html, then that's an easy way to make it easy to show the contents of the notebook to people who don't have Jupyter Notebook installed.
  • Gradescope does know how to render .ipynb files
  • "File" > "Download As" > "HTML (.html)"

DO NOT USE JUPYTER NOTEBOOKS FOR HW 8 IN DS 2000

(Consult with your DS 2001 instructor for their preference if you are interested in using jupyter notebooks for your DS 2001 project.)

Notebook structure

In general, you'd like your notebooks structured as follows:

In each cell, from the top to the bottom

1. Your header comment
2. Your imports
3. One function per cell (in general)