Running and Quitting

Overview

Teaching: 10 min
Exercises: 0 min

Questions

• How can I run Python programs?

Objectives

• Launch the Jupyter Notebook, create new notebooks, and exit the Notebook.

• Create Markdown cells in a notebook.

• Create and run Python cells in a notebook.

Python programs are plain text files.

• They have the .py extension to let everyone (including the operating system) know it is a Python program.
  • This is convention, not a requirement.
• It’s common to write them using a text editor but we are going to use the Jupyter Notebook to present the tutorials.
• The bit of extra setup is well worth it because the Notebook provides code completion and other helpful features.
• Notebook files have the extension .ipynb to distinguish them from plain-text Python programs.
  • Can export as “pure Python” to run from the command line.

Use the Jupyter Notebook for editing and running Python.

• The Anaconda package manager is an automated way to install the Jupyter notebook.
  • See the setup instructions for Anaconda installation instructions.
• It also installs all the extra libraries it needs to run.

• Once you have installed Python and the Jupyter Notebook requirements, open a shell and type:

  $ jupyter notebook
  

• This will start a Jupyter Notebook server and open your default web browser.
• The server runs locally on your machine only and does not use an internet connection.
• The server sends messages to your browser.
• The server does the work and the web browser renders the notebook.
• You can type code into the browser and see the result when the web page talks to the server.
• This has several advantages:
  • You can easily type, edit, and copy and paste blocks of code.
  • Tab complete allows you to easily access the names of things you are using and learn more about them.
  • It allows you to annotate your code with links, different sized text, bullets, etc. to make it more accessible to you and your collaborators.
  • It allows you to display figures next to the code that produces them to tell a complete story of the analysis.

Spyder

You can also use a Python Integrated Development Environment

PyCharm

You can also use a Python Integrated Development Environment

Jupyter notebook

Math with numbers

• Addition

2+3

5

• Multiplication

2*2

4

• More complex

9.81*10.2**2/2

510.3162

• Power

3 ** 2

9

Math with strings (?)

• Concatenation

"cat " + "dog"

'cat dog'

• repetition

"cat "*3 + "dog"

'cat cat cat dog'

• subtraction

"cat " - "dog"

...
TypeError: unsupported operand type(s) for -: 'str' and 'str'

Operators

• Addition

6 + 7

13

• Multiplication

6 * 7

42

• Division

6 / 7 

0.8571428571428571

• Power

6 ** 7 # power

279936

• Modulo

66 % 7  # Modulo (remainder)

3

Logic

• Less than

6 < 7

True

• less than or equal to

6 <= 7 

True

• equal to

6 == 7 

False

• greater than or equal to

6 >= 7 

False

• greater than

6 > 7 

False

• logical and

True and False 

False

• logical or

True or False

True

• logical not

not False

True

Key Points

• Python programs are plain text files.

• Use the Jupyter Notebook for editing and running Python.

• The Notebook has Command and Edit modes.

• Use the keyboard and mouse to select and edit cells.

• The Notebook will turn Markdown into pretty-printed documentation.

• Markdown does most of what HTML does.