Python Programming

Python is a high-level, general-purpose and a very popular programming language. Python programming languages is being used in web development, Machine Learning applications, along with all cutting edge technology in Software Industry. Python Programming Language is very well suited for Beginners, also for experienced programmers with other programming languages like C++ and Java.

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Python Programming Language

This specially designed Python tutorial will help you learn Python Programming Language in most efficient way, with the topics from basics to advanced (like Web-scraping, Django, Deep-Learning, etc.) with examples. Below are some facts about Python Programming Language:

  1. Python is currently the most widely used multi-purpose, high-level programming language.
  2. Python allows programming in Object-Oriented and Procedural paradigms.
  3. Python programs generally are smaller than other programming languages like Java.Programmers have to type relatively less and indentation requirement of the language, makes them readable all the time.
  4. Python language is being used by almost all tech-giant companies like-Google, Amazon, Facebook, Instagram, Dropbox, Uber… etc.
  5. The biggest strength of Python is huge collection of standard library which can be used for the following:
    • Machine Learning
    • GUI Applications (like Kivy, Tkinter, PyQt etc. )
    • Web frameworks like Django (used by YouTube, Instagram, Dropbox)
    • Image processing (like OpenCV, Pillow
    • Web scraping (like Scrapy, BeautifulSoup, Selenium)
    • Test frameworks
    • Text processing and many more..

Introduction to Python

Python is a widely used general-purpose, high level programming language. It was created by Guido van Rossum in 1991 and further developed by the Python Software Foundation. It was designed with an emphasis on code readability, and its syntax allows programmers to express their concepts in fewer lines of code.Python is a programming language that lets you work quickly and integrate systems more efficiently.There are two major Python versions: Python 2 and Python 3. Both are quite different.

Beginning with Python programming:

  1. Finding an Interpreter:

    Before we start Python programming, we need to have an interpreter to interpret and run our programs. There are certain online interpreters like GeeksforGeeks Online Compiler that can be used to run Python programs without installing an interpreter.

    Windows: There are many interpreters available freely to run Python scripts like IDLE (Integrated Development Environment) that comes bundled with the Python software downloaded from Python Download

    Linux: Python comes preinstalled with popular Linux distros such as Ubuntu and Fedora. To check which version of Python you're running, type “python” in the terminal emulator. The interpreter should start and print the version number.

    macOS: Generally, Python 2.7 comes bundled with macOS. You'll have to manually install Python 3 from http://python.org/.

  2. Writing our first program: Just type in the following code after you start the interpreter. Code: print("Sameer") Output: Sameer

    Let's analyze the script line by line.

    Line 1: [print(“Sameer”)] To print something on the console, print() function is used. This function also adds a newline after our message is printed (unlike in C).

    Note that in Python 2, “print” is not a function but a keyword and therefore can be used without parentheses. However, in Python 3, it is a function and must be invoked with parentheses.

    Python designed by Guido van Rossum at CWI has become a widely used general-purpose, high-level programming language.

Prerequisites:

  1. Emphasis on code readability, shorter codes, ease of writing
  2. Programmers can express logical concepts in fewer lines of code in comparison to languages such as C++ or Java.
  3. Python supports multiple programming paradigms, like object-oriented, imperative and functional programming or procedural.
  4. There exists inbuilt functions for almost all of the frequently used concepts
  5. Philosophy is “Simplicity is the best”.
Python Advantages and Applications

Python is a high-level, interpreted, and general-purpose dynamic programming language that focuses on code readability. It generally has small programs when compared to Java and C. It was founded in 1991 by developer Guido Van Rossum. Python ranks among the most popular and fastest-growing languages in the world. Python is a powerful, flexible, and easy-to-use language. In addition, the python community is very active. It is used in many organizations as it supports multiple programming paradigms. It also performs automatic memory management.

Advantages:

  1. Presence of third-party modules
  2. Extensive support libraries(NumPy for numerical calculations, Pandas for data analytics, etc.)
  3. Open source and large active community base
  4. Versatile, Easy to read, learn and write
  5. User-friendly data structures
  6. High-level language
  7. Dynamically typed language(No need to mention data type based on the value assigned, it takes data type)
  8. Portable and Interactive
  9. Interpreted Language
  10. Internet of Things(IoT) Opportunities

Applications

  1. GUI-based desktop applications
  2. Graphic design, image processing applications, Games, and Scientific/ computational Applications
  3. Web frameworks and applications
  4. Enterprise and Business applications
  5. Operating Systems
  6. Education
  7. Language Development
  8. Software Development
  9. Database Access

Organizations using Python :

  1. Google(Components of Google spider and Search Engine)
  2. Yahoo(Maps)
  3. YouTube
  4. Mozilla
  5. Microsoft
  6. Dropbox
  7. Spotify
  8. Cisco
  9. Quora
  10. Facebook
Python String

A string is a sequence of characters that can be a combination of letters, numbers, and special characters. It can be declared in python by using single quotes, double quotes, or even triple quotes. These quotes are not a part of a string, they define only starting and ending of the string. Strings are immutable, i.e., they cannot be changed. Each element of the string can be accessed using indexing or slicing operations.

Code: # Assigning string to a variable a = 'This is a string' print (a) b = "This is a string" print (b) c= '''This is a string''' print (c) Output: This is a string This is a string This is a string Code: def string_length(str1): count = 0 for char in str1: count += 1 return count print(string_length('w3resource.com')) Output: 14 Code: def find_longest_word(words_list): word_len = [] for n in words_list: word_len.append((len(n), n)) word_len.sort() return word_len[-1][0], word_len[-1][1] result = find_longest_word(["PHP", "Exercises", "Backend"]) print("\nLongest word: ",result[1]) print("Length of the longest word: ",result[0]) Output: Longest word: Exercises Length of the longest word: 9 Code: def remove_char(str, n): first_part = str[:n] last_part = str[n+1:] return first_part + last_part print(remove_char('Python', 0)) print(remove_char('Python', 3)) print(remove_char('Python', 5)) Output: ython Pyton Pytho
Python Arrays

An array is a collection of items stored at contiguous memory locations. The idea is to store multiple items of the same type together. This makes it easier to calculate the position of each element by simply adding an offset to a base value, i.e., the memory location of the first element of the array (generally denoted by the name of the array).
For simplicity, we can think of an array a fleet of stairs where on each step is placed a value (let's say one of your friends). Here, you can identify the location of any of your friends by simply knowing the count of the step they are on. Array can be handled in Python by a module named array. They can be useful when we have to manipulate only a specific data type values. A user can treat lists as arrays. However, user cannot constraint the type of elements stored in a list. If you create arrays using the array module, all elements of the array must be of the same type.

Arrays
Python Programming Arrays
Python Operators

Python Operators in general are used to perform operations on values and variables. These are standard symbols used for the purpose of logical and arithmetic operations. In this article, we will look into different types of Python operators.

  • OPERATORS: Are the special symbols. Eg- + , * , /, etc.
  • OPERAND: It is the value on which the operator is applied.

PRECEDENCE:

  • P - Parentheses
  • E - Exponentiation
  • M - Multiplication (Multiplication and division have the same precedence)
  • D - Division
  • A - Addition (Addition and subtraction have the same precedence)
  • S - Subtraction
Operators
Python Programming Operators
Python Functions

Python Functions is a block of statements that return the specific task. The idea is to put some commonly or repeatedly done tasks together and make a function so that instead of writing the same code again and again for different inputs, we can do the function calls to reuse code contained in it over and over again.

Functions
Python Functions Syntax
Reference