Python Programming

• Python Programming
  • Introduction to Python Programming
    • Installing Python
    • Interactive Python Shell
    • Installing Visual Studio Code
    • Setting Up Python in Visual Studio Code
    • Writing Your First Python Program in VS Code
    • Python Comments
      • Single-Line Comments
      • Multiline Comments (Docstrings)
    • Summary
  • Python Built-in Functions
    • The print() Function
    • The len() Function
    • The type() Function
    • The input() Function
    • The range() Function
    • The abs(), min(), max(), and sum() Functions
    • The enumerate() Function
    • The dir() Function
    • Builtin Functions Summary

WEEK 2 >>

WEEK 1 | WEEK 2 | WEEK 3 | WEEK 4 | WEEK 5 | WEEK 6

Introduction to Python Programming

Python is a versatile and beginner-friendly programming language known for its simplicity and readability. It's widely used in various fields, such as web development, data science, automation, and artificial intelligence. This guide will walk you through setting up Python, running an interactive shell, installing Visual Studio Code (VS Code), and writing your first Python program: "Hello World!".

Installing Python

Before writing any Python code, you need to install Python on your computer. Follow these steps:

• Step 1: Go to the official Python website.

• Step 2: Click on the Downloads section and choose the version for your operating system (Windows, macOS, or Linux).

• Step 3: Run the downloaded installer.

  • For Windows users, during installation, make sure to check the box labeled "Add Python to PATH". This makes running Python from the command line easier.

• Step 4: Verify the installation by opening a terminal (Command Prompt for Windows, or Terminal for macOS/Linux) and typing:

  python --version

  You should see the installed Python version printed.

Interactive Python Shell

Python comes with an interactive shell that allows you to run Python commands immediately. Here's how to open it:

• Step 1: Open your terminal or command prompt.
• Step 2: Type python (or python3 on some systems) and hit Enter. This will start the Python shell.

You’ll see a prompt like this:

Python 3.x.x (default, Mar 18 2021, 13:41:09)
[GCC 7.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

This is the Python interactive shell, where you can run Python commands directly. Try typing:

print('Hello World!')

It should print:

Hello World!

You’ve just written your first Python program in the interactive shell!

Installing Visual Studio Code

To write more complex Python programs, you’ll want to use a code editor like Visual Studio Code (VS Code). Follow these steps to install and set up VS Code:

• Step 1: Go to the Visual Studio Code website.
• Step 2: Download the appropriate version for your operating system (Windows, macOS, or Linux).
• Step 3: Run the installer and follow the setup instructions.
• Step 4: Once installed, open VS Code.

Setting Up Python in Visual Studio Code

Now, let's set up Python in VS Code.

• Step 1: Install the Python extension for VS Code:

  • Open VS Code and click on the Extensions icon (on the left-hand toolbar).
  • Search for "Python" and install the official Python extension by Microsoft.

• Step 2: Ensure VS Code is using the correct Python interpreter:

  • Press Ctrl+Shift+P (Windows) or Cmd+Shift+P (macOS) to open the Command Palette.
  • Type Python: Select Interpreter and choose the Python version you installed.

Writing Your First Python Program in VS Code

Let’s write the same "Hello World!" program in VS Code.

• Step 1: Create a new file in VS Code by selecting File > New File.

• Step 2: Save the file with a .py extension (e.g., hello.py).

• Step 3: Write the following code in the file:

  print('Hello World!')

• Step 4: Run the Python code:

  • You can run it directly within VS Code by pressing Ctrl+F5 (Windows) or Cmd+F5 (macOS).

  • Alternatively, open the terminal within VS Code (Ctrl+ `) and type:

    python hello.py

You should see the output:

Hello World!

Congratulations! You've successfully set up Python, learned how to use the interactive shell, installed VS Code, and written your first Python program. This is just the beginning of your Python journey!

---

Python Comments

In Python, comments are an essential part of writing clean and understandable code. Comments help both the programmer and others understand what the code is doing. Python supports two types of comments: single-line comments and multiline comments. In this section, we will explain these comment types and the print() function.

Single-Line Comments

A single-line comment in Python begins with a hash symbol (#). Everything following the hash on that line is considered a comment and is ignored by the Python interpreter.

Single Line Comment Example:

# A hash symbol is a single line comment
# The purpose of a comment is to make our code readable and maintainable

In this example, both lines are comments and will not be executed. They exist to describe the purpose of the code that follows, helping the programmer understand what’s happening.

# The `print()` function is used to display output on the screen. It can take one or more arguments and print them, separated by spaces.
print('Hello', 'World', 2024, 'Data Analysis with Python - Autumn 2024')

Explanation:

• This line of code prints four separate items: 'Hello', 'World', 2024, and 'Data Analysis with Python - Autumn 2024'.
• The print() function separates each of these inputs by a space and displays them in a single line:

  Hello World 2024 Data Analysis with Python - Autumn 2024

You can pass any combination of data types (strings, integers, etc.) to print(), and it will display them on the console.

Multiline Comments (Docstrings)

In Python, you can create multiline comments by enclosing the comment text within triple quotes (''' or """). These are often used for longer explanations or documentation. Multiline comments are sometimes referred to as docstrings, especially when used inside functions or classes to document their purpose.

Multiline Comment Example:

'''
A multiline comment allows us to write a comment
on several lines and
sometimes it can be used as good documentation
'''

or

"""
A multiline comment allows us to write a comment
on several lines and
sometimes it can be used as good documentation
"""

Explanation:

• Both single quotes (''') and double quotes (""") can be used to write multiline comments. The choice between them is a matter of preference and style.
• These multiline comments are helpful for providing detailed explanations of code or for documenting larger sections.

Summary

• Single-line comments (#) are useful for short, concise comments.
• Multiline comments (''' or """) are helpful for more extensive explanations or documentation.
• The print() function is a fundamental tool for displaying outputs, allowing multiple arguments separated by spaces to be printed in a single line.

By using comments effectively, you can make your code more readable and maintainable, while the print() function provides an easy way to output text and other data types during the execution of your Python programs.

---

Python Built-in Functions

In Python, functions are a key tool for writing reusable and modular code. There are two main types of functions in Python: built-in functions and custom functions.

• Built-in Functions: Predefined functions that are available in Python without the need to import any external modules.
• Custom Functions: Functions defined by the user to solve specific problems or perform specific tasks.

This document focuses on various built-in functions in Python, including how to use them and what they do.

---

The print() Function

The print() function is one of the most commonly used built-in functions in Python. It displays the output of any data type (integers, strings, lists, etc.) on the screen.

print(10, type(10))
print(9.81, type(9.81))
print('Asabeneh Yetayeh', 'Finland', 'Helsinki', 250, ['HTML', 'CSS', 'JS'], sep=', ')

Explanation:

• print() takes any number of arguments and prints them, separated by spaces by default. You can customize the separator using the sep parameter.
• type() shows the type of the data passed to it, like integer, float, string, etc.

Output:

10 <class 'int'>
9.81 <class 'float'>
Asabeneh Yetayeh, Finland, Helsinki, 250, ['HTML', 'CSS', 'JS']

---

The len() Function

The len() function returns the number of items in a sequence (like strings, lists, etc.).

print(len('cat'))
print(len('Finland'))

Explanation:

• len() works on any sequence type such as strings, lists, tuples, etc., and returns the length.

Output:

3
7

---

The type() Function

The type() function returns the type of a given object.

print(10, type(10))
print(1 + 4j, type(1 + 4j))

Explanation:

• type() shows the data type of any object, whether it's an integer, float, complex number, string, etc.

---

The input() Function

The input() function is used to take input from the user.

name = input('Enter your name: ')
print('Hello, ' + name)

Explanation:

• input() takes a string as a prompt and waits for the user to input text. The input is always returned as a string.

---

The range() Function

The range() function generates a sequence of numbers, which can be converted into a list or iterated through.

print(list(range(0, 10)))
print(list(range(0, 101, 2)))

Explanation:

• range(start, end, step) generates a sequence of numbers from start to end-1, with a step increment of step.
• You can convert a range object into a list using list().

---

Python provides various built-in functions for working with different data types like lists, sets, dictionaries, and tuples.

print(set(['English', 'French', 'Finnish', 'Swedish', 'Finnish']))
print(dict(name='Asab', age=250))

Explanation:

• set() creates a set, removing duplicates.
• dict() creates a dictionary with key-value pairs.

---

The abs(), min(), max(), and sum() Functions

These built-in functions perform basic mathematical operations.

print(abs(-5))
print(min(-2, 10, 5, 20))
print(max(-2, 10, 5, 20))
print(sum([1, 2, 3, 4, 5]))

Explanation:

• abs() returns the absolute value.
• min() and max() return the smallest and largest values, respectively.
• sum() adds up all elements in a list.

---

The enumerate() Function

The enumerate() function adds a counter to an iterable (like a list) and returns it as an enumerate object.

countries = ['Finland', 'Sweden', 'Norway']
print(list(enumerate(countries)))

Explanation:

• enumerate() is useful when you need to iterate over a list while keeping track of the index.

---

The dir() Function

The dir() function returns a list of all attributes and methods available for an object.

print(dir('hello'))

Explanation:

• dir() helps you explore the methods associated with a particular object, such as a string, list, or function.

---

Builtin Functions Summary

• Python's built-in functions like print(), len(), input(), and range() are powerful tools for solving common problems and tasks.
• Functions like abs(), min(), max(), sum(), and enumerate() are useful for working with numbers and sequences.
• Python's data types—lists, sets, dictionaries, and tuples—can be manipulated easily using functions like list(), set(), dict(), etc.

Understanding and effectively using these built-in functions is a fundamental part of programming in Python

---

WEEK 2 >>