Python Tutorial: Learn Python from Scratch

Python has long occupied one of the top positions in popularity charts. According to Google Trends and GitHub, Python surpassed Java and JavaScript to become the most popular programming language in 2020. GitHub ascertained popularity levels based on the most number of tutorial searches on Google. Python ranks third among the top five most widely used programming languages among software developers as of 2021. In addition, Python ranks high in the latest PYPL Popularity of Programming Language and TIOBE Indexes.

In this Python tutorial for beginners, we’ll walk you through Python fundamentals to help you understand the language from scratch!

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What is Python?

Python is a high-level, object-oriented, and general-purpose programming language created by Guido van Rossum. It was first released on February 20, 1991. While the programming language’s name conjures up images of a slithering reptile, the term ‘Python’ actually comes from ‘Monty Python’s Flying Circus,’ an old comedy sketch series on BBC television. 

Rossum’s vision of Python was an open-source, powerful, easy, and intuitive language with easily understandable code and short development cycle. More than 20 years later since Rossum defined his goals, Python has not only lived up to its creator’s intentions but also become one of the key programming languages alongside Java, JavaScript, etc. Prominent companies like Google, Instagram, and Dropbox, heavily count on Python for their versatile array of products and platforms.

Next, in this Python tutorial for beginners, we’ll look at its many useful features which make it so valuable and popular.

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Features

Listed below are some Python features that make it extremely popular:

• Being an object-oriented language, Python allows code reusability and enables developers to build applications with minimal coding.
• Python can be easily integrated with other programming languages like Java, C, C++, and many more. Like Java, C, and C++, Python runs code by line and makes debugging easier.
• Python offers a vast range of standard libraries for various fields such as web development, machine learning, and scripting.
• Python is embeddable, meaning that the Python source code can be used in another programming language and vice versa.
• Python is a cross-platform language, meaning it can run equally on different platforms like UNIX, Linux, Windows, Mac, etc. So, programmers need to write code only once.
• Most importantly, Python is free, open-source, and easy to learn. Moreover, its straightforward syntax makes Python the recommended programming language for beginners.

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Applications 

The general-purpose nature of Python makes it ubiquitous in almost every arena of software development and other emerging fields. It is used for:

• Software Development
• Web Applications
• Desktop GUI Applications
• Image Processing Applications
• Enterprise Applications
• 3D CAD Applications
• Audio and Video-based Applications
• Business Applications
• Console-based Applications
• Artificial Intelligence

Python Keywords

Python keywords are reserved words that cannot be used as names of variables, functions, or any other identifier. Keywords are case-sensitive and must be written as they are. Python 3 has over 30 reserved keywords, out of which only None, True, and False begin with an upper case letter. Here’s a list of all the Python keywords:

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Source

Python Identifiers

In Python, an identifier is a name given to a class, variable, function, etc., and helps distinguish one entity from the other. Also, there are specific rules for writing Python identifiers. For instance, an identifier can be a combination of digits, upper and lower case letters, and underscores, an identifier name cannot start with a digit, it cannot contain special symbols, and a keyword cannot be used as an identifier. 

Variable1, var_1, MyVar are all valid examples of identifiers.

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Python Variables

A variable is a reserved memory location used to store data. It can be thought of as a container that stores data and can be changed in the program’s course later. In Python, naming a variable follows the same rules as identifiers. Also, we do not need to specify the variable type in Python since the language can infer it on its own. 

For example, num = 20. Here, we have created a variable num and assigned the value 20 to it.

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Python Constants

A constant is a Python variable whose value cannot be changed. Typically, a constant in Python is declared and assigned in a module which is a new file imported to the main file and contains functions, variables, etc. Constants are usually written in upper case letters.

For example, PI = 3.14 is an example of a constant.

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Python Literals

A Python literal is data given in a constant or variable and can be of different types.

• A string literal in Python is a sequence of characters enclosed within single, double, or triple quotations. Triple quotation marks are used in case of strings written in multiple lines. 

Examples:

strings = “Let’s learn Python”

Multiline_str = “”” Welcome

to

Python tutorial”””

• A numeric literal is unchangeable and can be one of three different types: Integer, Float, and Complex. Integers can be positive or negative numbers with no fractional part, float (floating point) are real numbers with both integer and fractional parts, and complex numbers have a real and imaginary part.

Examples:

a = 100 //Integer

b = 12.6 //Float

c = 2+3.14j //Complex

• A boolean literal can have one of two values: True or False.
• Python has a special literal None used to specify that a field has not been created.
• Python has four different literal collections: List literals, Dict literals, Tuple literals, Tuple literals, and Set literals.

Python Data Types

In Python, every value has a data type. A data type is a class, and a variable is an object (instance) of the class. Some of the vital Python data types are listed below:

• Python list is an orderly sequence of items enclosed within square brackets and separated by commas. All the list items need not be of the same type.

Example:

x = [4.5, 6, ‘Python’]

• Python numbers are another data type consisting of integers, complex numbers, and floating-point numbers. 
• Like a Python list, a tuple refers to an ordered sequence of comma-separated items. However, unlike lists, Python tuples are immutable and are refined within parentheses.

tup = (6, 1+3j, ‘Python’)

• Another Python data type is strings, a sequence of characters enclosed within single, double, or triple quotations.
• A Python set is an unordered collection of items separated by commas and enclosed within braces. 

Examples:

s = {3,1,4,2,5}

• A Python dictionary is a collection of key-value pairs typically used for vast datasets. It is defined within braces, and a key is used to retrieve its respective value, not vice versa.

Example:

>>> d = {4:’value’,’key’:5}

>>> type(d)

<class ‘dict’>

Python Basic Operators

Python operators are special symbols that perform arithmetic or logical computations. The different types of Python operators are :

• Arithmetic operators (+, -, *, /, %, //, **) 
• Comparison operators (>, <, ==, !=, >=, <=) 
• Logical operators (and, or, not) 
• Bitwise operators (AND, OR, NOT, XOR, right shift, left shift)
• Assignment operators (=, +=, -=, *=, /=, %=, //=, **=, &=, |=, ^=, >>=, <<=)
• Special operators: identity operators (is, is not) and membership operators (in, not in)

Basic Syntax of Python

We will wrap up this  Python tutorial for beginners with a simple program to understand the syntax. 

The following Python program example adds two numbers and prints the sum.

# Python program to add two numbers

a = 15

b = 6.3

# Adding two numbers

sum = a + b

# Displaying the sum

print(‘The sum of {0} and {1} is {2}’.format(a, b, sum))

Output:

The sum of 15 and 6.3 is 21.3

Summary 

Python is a general-purpose, object-oriented programming language widely popular among beginners and developers. Python has applications in several areas, including artificial intelligence, thanks to its many valuable features. In this Python tutorial for beginners, we discussed some fundamental concepts in Python.

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