Installing Python

Python distribution is available for a large number of platforms. You need to download only the binary code applicable for your platform and install Python.

If the binary code for your platform is not available, you need a C compiler to compile the source code manually. Compiling the source code offers more flexibility in terms of choice of features that you require in your installation.

Here is a quick overview of installing Python on various platforms −

Unix and Linux Installation

Follow these steps to install Python on Unix/Linux machine.

• Open a Web browser and go to https://www.python.org/downloads
• Follow the link to download zipped source code available for Unix/Linux.
• Download and extract files.
• Editing the Modules/Setup file if you want to customize some options.
• run ./configure script
• make
• make install

This installs Python at the standard location /usr/local/bin and its libraries at /usr/local/lib/pythonXX where XX is the version of Python.

Windows Installation

Follow these steps to install Python on Windows machine.

• Open a Web browser and go to https://www.python.org/downloads
• Follow the link for the Windows installer python-XYZ.msi file where XYZ is the version you need to install.
• To use this installer python-XYZ.msi, the Windows system must support Microsoft Installer 2.0. Save the installer file to your local machine and then run it to find out if your machine supports MSI.
• Run the downloaded file. This brings up the Python install wizard, which is really easy to use. Just accept the default settings and wait until the install is finished.

Macintosh Installation

If you are on Mac OS X, it is recommended that you use Homebrew to install Python 3. It is a great package installer for Mac OS X and it is really easy to use. If you don't have Homebrew, you can install it using the following command −

$ ruby -e "$(curl -fsSL
https://raw.githubusercontent.com/Homebrew/install/master/install)"

We can update the package manager with the command below −

$ brew update

Now run the following command to install Python3 on your system −

$ brew install python3

Setting up PATH

Programs and other executable files can be in many directories, so operating systems provide a search path that lists the directories that the OS searches for executables.

The path is stored in an environment variable, which is a named string maintained by the operating system. This variable contains information available to the command shell and other programs.

The path variable is named as PATH in Unix or Path in Windows (Unix is case-sensitive; Windows is not).

In Mac OS, the installer handles the path details. To invoke the Python interpreter from any particular directory, you must add the Python directory to your path.

Setting Path at Unix/Linux

To add the Python directory to the path for a particular session in Unix −

• In the csh shell
  Type setenv PATH "$PATH:/usr/local/bin/python" and press Enter.
• In the bash shell (Linux)
  Type export ATH = "$PATH:/usr/local/bin/python" and press Enter.
• In the sh or ksh shell
  Type PATH = "$PATH:/usr/local/bin/python" and press Enter.

Note − /usr/local/bin/python is the path of the Python directory.

Setting Path at Windows

To add the Python directory to the path for a particular session in Windows −

• At the command prompt − type path %path%;C:\Python and press Enter.

Note − C:\Python is the path of the Python directory.

Running Python

Let us now see the different ways to run Python. The ways are described below −

Interactive Interpreter

We can start Python from Unix, DOS, or any other system that provides you a command-line interpreter or shell window.

• Enter python at the command line.
• Start coding right away in the interactive interpreter.

$python # Unix/Linux

or

python% # Unix/Linux

or

C:> python # Windows/DOS

Here is the list of all the available command line options −

S.No.	Option & Description
1	-d It provides debug output.
2	-o It generates optimized bytecode (resulting in .pyo files).
3	-S Do not run import site to look for Python paths on startup.
4	-v Verbose output (detailed trace on import statements).
5	-x Disables class-based built-in exceptions (just use strings); obsolete starting with version 1.6.
6	-c cmd Runs Python script sent in as cmd string.
7	File Run Python script from given file.

Script from the Command-line

A Python script can be executed at the command line by invoking the interpreter on your application, as in the following −

$python script.py # Unix/Linux

or,

python% script.py # Unix/Linux

or,

C:> python script.py # Windows/DOS

Note − Be sure the file permission mode allows execution.

Integrated Development Environment

You can run Python from a Graphical User Interface (GUI) environment as well, if you have a GUI application on your system that supports Python.

• Unix − IDLE is the very first Unix IDE for Python.
• Windows − PythonWin is the first Windows interface for Python and is an IDE with a GUI.
• Macintosh − The Macintosh version of Python along with the IDLE IDE is available from the main website, downloadable as either MacBinary or BinHex'd files.

If you are not able to set up the environment properly, then you can take help from your system admin. Make sure the Python environment is properly set up and working perfectly fine.

We can also use another Python platform called Anaconda. It includes hundreds of popular data science packages and the conda package and virtual environment manager for Windows, Linux and MacOS. You can download it as per your operating system from the link https://www.anaconda.com/download/

For this tutorial we are using Python 3.6.3 version on MS Windows.