Running and Quitting

Overview

Teaching: 5 min
Exercises: 0 min

Questions

• How can I run Python programs?

Objectives

• Launch iPython.

• Run some simple python commands.

• Exit the iPython interpreter.

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.

Start iPython

$ ipython

• This will start a iPython interpreter.
• The iPython interpreter provides several advantages over the standard Python interpreter:
  • Tab completion allows you to easily access the names of things you are using and learn more about them
  • Smart up-down history allows you to quickly access and re-run old commands
  • Use of some simple terminal commands like ls, cd, pwd, etc.
  • Inline help documentation using “?”

The iPython interpreter

A few simple commands

Upon executing the iPython command, the following prompt will appear at the bottom of your screen.

In [1]:

The In portion indicates that iPython is waiting for input and the [1] indicates that this is the first command we’ll run in the iPython session.

Let’s start by running a few simple commands to get a feel for interacting with this interpreter.

Type the following command and press return.

In [1]: 2 + 7

After pressing return you should see something like the following.

Out [1]: 9

Here the Out is indicating that this is the output from the code we executed in command [1].

For the remainder of the workshop, these lessons won’t include the input/output portions shown here but rather just the commands and resulting output.

Installing iPython on your own machine

• The Anaconda package manager is an automated way to install the iPython on your own machine.
  • 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 iPython requirements, open a shell and type:

Key Points

• Use iPython for editing and running Python.

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