Getting Started with Python

Objectives

• Have a working Python environment on the computers.
• Understand the importance of choosing and using an IDE.
• Introduction to basic Python concepts.
• Grasp the concept of a program and how Python fits into it.
• Get hands-on experience by writing and running a first Python program.

The first steps to get started with programming using the Python language are:

• download and install Python to your computer
• download, install and if needed configure an IDE (Integrated Development Environment) to write your Python programs.

SourceResult

print("Hello, World!")
for i in range(5):
    print(i)

Hello, World! 0 1 2 3 4

Installing a Python environment

Follow these steps to install Python to your computer. The exact steps may vary depending on your operating system (Windows, macOS, or Linux).

Download Python

There are a couple of options here:

Microsoft Store Package

• This is the most straightforward method, especially for when just starting out. It is designed for students and others using Python for the first time.
• On their home page, search for "Python" or use this link: https://www.microsoft.com/en-gb/search/shop?q=python
• Select the app with the highest version number (at time of writing this was 3.11)
• Click Get
• Wait for the application to download and the click Install

The full package:

• Visit the official Python website at https://www.python.org/downloads/
• You'll see the latest versions of Python available for download. Choose the version that is appropriate for your operating system. For most users, it's Python 3.x (e.g., Python 3.8, Python 3.9, etc.), as Python 2 is no longer supported. At time of writing the latest version was Python 3.12.

2. Download the Installer:

• Click on the download link for the Python version you've chosen.
• If you're using Windows, you'll likely download an executable installer (.exe) file. For macOS, it will be a disk image (.dmg) file. For Linux, it might be a tarball (.tar.gz) or another format, depending on your distribution.

3. Run the Installer:

• For Windows: Double-click the downloaded .exe file and follow the installation wizard's instructions. Make sure to check the box that says "Add Python x.x to PATH" during installation to make Python accessible from the command line.
• For macOS: Double-click the .dmg file and follow the instructions to install Python.
• For Linux: Open a terminal and navigate to the directory where you downloaded the tarball. Extract it and follow the README or installation instructions provided with your distribution.

> python --version
Python 3.10.5

Note

If you encounter any issues or would like further help go to https://realpython.com/installing-python/ and follow the instructions there

The Python interactive environment

• Enter python in your terminal (command) window, this will load the Python interactive environment and means you can run Python commands here.
• Sometimes known as the REPL, which stands for "Read-Evaluate-Print-Loop".
• Try the following examples which introduce some of the fundamental concepts of Python:

Basic Arithmetic Operations:

• In Python, you can perform basic arithmetic operations directly in the interactive environment.
• At the prompt, try the following and record your answers:

>>> 2 + 3
>>> 5 - 1
>>> 4 * 6
>>> 10 / 3
>>> 10 // 3

Working with Variables:

• A variable is a name that we give to some data which is stored in the computer's memory. We can create variables to store and manipulate data in the interactive environment.
• At the prompt, try the following and observe the results:

>>> x = 5
>>> y = 3
>>> sum_result = x + y
>>> product_result = x * y
>>> sum_result
>>> product_result

Strings and String Operations:

• Strings are collections of characters, usually assigned to a variable.
• Strings will always be surrounded by quote characters (either single quote or double quote)
• At the prompt, try the following and observe the results:

>>> greeting = "Hello"
>>> greeting
>>> name = "Alice"
>>> name

• String can be joined together, known as concatenation:

>>> full_greeting = greeting + " " + name
>>> full_greeting

• Strings can be processed using some useful built-in functions:

>>> greeting_length = len(greeting)
>>> greeting_length
>>> uppercase_name = name.upper()
>>> uppercase_name

Lists and List Operations:

• Lists are a fundamental data structure in Python, they are collections of data items with a common name.
• At the prompt, try the following and observe the results:

>>> fruits = ["apple", "banana", "cherry"]

• To access the elements, or items, in the list we use an index for its position (starting at \(0\))

>>> first_fruit = fruits[0]
>>> second_fruit = fruits[1]

• Items can be added or removed from the list:

>>> fruits.append("orange")
>>> fruits.remove("banana")

• Review the results:

>>> fruits
>>> first_fruit
>>> second_fruit

Info

To exit from the interactive environment, enter the command exit() or quit() or use the shortcut keys Ctrl+D (Windows)

Install a Code Editor or IDE

• While you can write Python code using the interactive environment it soon becomes too difficult and we need to write our code in a file which can then be run by the Python interpreter. For this we use an IDE, or Interactive Development Environment.
• The IDE will come with an editor (for writing our code and options to save our file etc), syntax highlighting, line numbers, a debugging environment and a host of other features.
• Working with an IDE that you like and can get familiar with is a really important aspect of a programmer's workflow.
• There are several IDEs available for Python and we'll not cover the specific instructions for each.
• Your Python installation will come with a default IDE called IDLE
• You might like to try alternatives (as IDLE can be tricky and its debugging environment is not ideal), e.g.
• Thonny
• Visual Studio Code
• PyCharm
• Alternatively you can use an online environment such as that provided by repl.it
• With your chosen editor make sure you know how to create a new file and save.

That's it! Python should now be installed on your home computer. You can start writing and running Python scripts in your chosen development environment.

Remember to keep your Python installation updated as new versions are released with bug fixes and improvements. You can check for updates and install them using the pip package manager, which usually comes bundled with Python. Use the following command to upgrade pip and check for Python package updates:

> pip install --upgrade pip
> pip list --outdated

Your first program

The convention when learning any new programming language is to write a program that displays the string "Hello, World!" on the screen. You can read about why this is the case here.

With Python this is very easy:

SourceResult

print("Hello, World!")

Hello, World!

That's it! We use the built-in Python function, print(), and provide this function with the text we want to display inside quotation marks. You can use single or double quote, just be consistent.

• In your IDE create a new file, save it with a suitable name e.g. 'hello.py'.
• Enter the statement to print as in the code snippet above, and re-save the file
• Run the file using e.g. 'Run Module' in IDLE, 'Run Current Module' in Python or click the play button in VSCode
• Most IDEs will run the current file using the F5 key.
• Alternatively at a terminal window, in the directory where the file has been saved you can type the following to run your program: C:\PythonFiles\Hello\python hello.py

Note

All Python code files, sometimes called scripts, should be saved with the file extension '.py'

Questions

1. What are the general steps to install Python on your home computer?

Download the installer and click 'Next' repeatedly

Visit a random website and download Python

Download Python from the official Python website and follow the installation instructions

Python cannot be installed on home computers

It's important to download Python from the official Python website (https://www.python.org) to ensure you are getting a legitimate, up-to-date version of the software. The installation instructions provided are straightforward and guide you through the process to ensure Python is installed correctly.

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2. Which version of Python should you choose for most users?

Python 2.x

Python 3.x

Python 4.x

Python 1.x

Python 3.x is the recommended version for most users because it is the current and actively maintained version. Python 2.x has reached the end of its life and is no longer supported, so using Python 3 ensures compatibility with modern libraries and tools.

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3. What does the 'Add Python x.x to PATH' option during installation do?

It adds Python to the Windows Registry

It creates a shortcut on the desktop

It adds Python to the system's PATH environment variable

It installs additional Python libraries

Adding Python to the PATH environment variable allows you to run Python from the command prompt or terminal without having to specify the full path to the Python executable. This makes it easier to use Python from any directory.

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4. How can you check if Python is installed correctly on your computer?

By opening Microsoft Word

By typing python --version in the command prompt or terminal

By creating a new Python file

By checking your email

Typing python --version in the command prompt or terminal will display the installed version of Python, confirming that Python is installed and correctly configured.

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5. What command can you use to start the Python interactive environment in your terminal or command prompt?

start python

run python

python

start

Simply typing python (or python3 on some systems) in the terminal or command prompt starts the Python interactive environment, also known as the REPL (Read-Eval-Print Loop), where you can enter and execute Python code interactively.

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6. What is the result of the expression 10 / 3 in Python?

3.3333333333333335

3.0

4

10

In Python, the / operator performs floating-point division, which means the result is a decimal (float) value. The division of 10 by 3 results in a float with many decimal places: 3.3333333333333335.

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7. What does the len() function do in Python?

Returns the length of a string or list

Converts a string to uppercase

Performs basic arithmetic operations

Creates a new list

The len() function in Python is used to determine the number of elements in a list or the number of characters in a string. It returns an integer representing this count.

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8. How do you access elements in a list in Python?

Using square brackets and the element's value

Using the get() function

Using parentheses and an index

Lists cannot be accessed in Python

In Python, elements in a list are accessed using square brackets ([]) and an index (an integer representing the position of the element). For example, my_list[0] would access the first element in the list.

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9. Which Python function is used to join two or more strings together?

add()

concatenate()

merge()

+ operator

In Python, the + operator is used to concatenate (join) two or more strings together. For example, 'Hello' + ' ' + 'World' results in 'Hello World'.

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10. What is the purpose of an Integrated Development Environment (IDE) when working with Python?

To download Python packages

To create Python programs

To run Python scripts in a web browser

To play Python games

An Integrated Development Environment (IDE) provides tools to write, debug, and test Python programs more efficiently. It typically includes features like code editors, debuggers, and automation tools that streamline the development process.

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