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Step-by-step installation

Novice data scientists who have never used Python (who likely don't have the language readily installed on their machines) need to first download the installer from the main website of the project, www.python.org/downloads/, and then install it on their local machine.

This section provides you with full control over what can be installed on your machine. This is very useful when you have to set up single machines to deal with different tasks in data science. Anyway, please be warned that a step-by-step installation really takes time and effort. Instead, installing a ready-made scientific distribution will lessen the burden of installation procedures and it may be well-suited for first starting and learning because it saves you time and sometimes even trouble, though it will put a large number of packages (and we won't use most of them) on your computer all at once. Therefore, if you want to start immediately with an easy installation procedure, just skip this part and proceed to the next section, Scientific distributions.

This being a multiplatform programming language, you'll find installers for machines that either run on Windows or Unix-like operating systems.

Remember that some of the latest versions of most Linux distributions (such as CentOS, Fedora, Red Hat Enterprise, and Ubuntu) have Python 2 packaged in the repository. In such a case, and in the case that you already have a Python version on your computer (since our examples run on Python 3), you first have to check what version you are exactly running. To do such a check, just follow these instructions:

Open a python shell, type python in the terminal, or click on any Python icon you find on your system.
Then, after starting Python, to test the installation, run the following code in the Python interactive shell or REPL:

>>> import sys
>>> print (sys.version_info)

If you can read that your Python version has the major=2 attribute, it means that you are running a Python 2 instance. Otherwise, if the attribute is valued 3, or if the print statement reports back to you something like v3.x.x (for instance, v3.5.1), you are running the right version of Python, and you are ready to move forward.

To clarify the operations we have just mentioned, when a command is given in the terminal command line, we prefix the command with $>. Otherwise, if it's for the Python REPL, it's preceded by >>>.

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