Jupyter is our favored choice throughout this book. It is used to clearly and effectively illustrate and narrate operations using scripts and data, and their consequent results.

Though we strongly recommend using Jupyter, if you are using a REPL or an IDE, you can use the same instructions and expect identical results (except for the print formats and extensions of the returned results).

If you do not have Jupyter installed on your system, you can promptly set it up by using the following command:

$> pip install jupyter

You can find complete instructions about Jupyter installation (covering different operating systems) at http://jupyter.readthedocs.io/en/latest/install.html.

After installation, you can immediately start using Jupyter by calling it from the command line:

$> jupyter notebook 

Once the Jupyter instance has opened in the browser, click on the New button; in the Notebooks section, choose Python 3 (other kernels may be present in the section depending on what you installed).

At this point, your new empty notebook will look like the following image: 

At this point, you can start entering the commands in the first cell. For instance, you may start trying typing the following into the cell where the cursor is flashing:

In: print ("This is a test") 

After writing in the cell, you just press the Play button which is below the cell tab (or, as a keyboard hotkey, you can push shift and enter buttons at the same time) to run it and obtain an output. Then, another cell will appear for your input. As you are writing in a cell, if you press the plus button on the menu bar, you will get a new cell, and you can move from one cell to another using the arrows on the menu.

Most of the other functions are quite intuitive, and we invite you to try them. In order to learn how Jupyter works, you may use a quick start guide such as http://jupyter-notebook-beginner-guide.readthedocs.io/en/latest/, or buy a book specializing in Jupyter functionalities.

For illustrative purposes, just consider that every Jupyter block of instructions has a numbered input statement and an output of one. Therefore, you will find the code presented in this book structured in two blocks, at least when the output is not trivial at all. Otherwise, expect only the input part:

In: <the code you have to enter> Out: <the output you should get>

As a rule, you just have to type the code after In: in your cells and run it. You can then compare your output with the output that we may provide using Out:, followed by the output that we actually obtained on our computers when we tested the code.