Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Learning Python

Learning Python

Learning Python.

This was a Python introduction presentation meant for beginners.
This slide is a part of a the Course "Learn Python, Django & Web Development".
Read More here https://github.com/kabirbaidhya/learn-python-django-web.

Kabir Baidhya

March 05, 2017
Tweet

More Decks by Kabir Baidhya

Other Decks in Programming

Transcript

  1. Python is a programming language that lets you work quickly

    and integrate systems more effectively. www.python.org “ “
  2. Why Python? 1. Easy to learn yet very powerful 2.

    General purpose language that could be used almost everywhere 3. Flexibility and scalability 4. Multi-paradigm: object oriented, functional, procedural etc. 5. Popular language, big community 6. Fun to work with 7. Career Opportunities
  3. Python is everywhere CLI applications Web Apps backened / APIs

    GUI applications Network applications System Administration / DevOps Scienti c Applications Data Science Projects Machine Learning / Deep learning and much more
  4. Python 2 or 3? There are two versions of python

    currently in use python 2.7 & python 3. So, begineers often come up with question “Should I choose Python 2 or Python 3”?
  5. Current State 1. Most production applications today use Python 2.7.

    2. Python 3 is ready for the production deployment of applications today. 3. Python 2.7 will only receive necessary security updates until 2020. 4. The brand name “Python” encapsulates both Python 3 and Python 2.
  6. So... 3? Yes, start with python 3.x but familiarizing yourself

    with Python 2.7 will be very useful. In case if you have to work with legacy projects in the future you might need to know 2.x too.
  7. Installa on Linux Python comes out of the box in

    most modern linux distros like Debian, Fedora, Centos etc. In case it's not preinstalled you can always download it from the of cial website. Windows You can download the installer from the of cial website. https://www.python.org/downloads/
  8. Code Editors You could use any code editors out there

    to write code in python as long as it supports syntax highlighting. Here are some recommended editors/IDEs: Microsoft Vscode Atom Sublime Vim Jetbrains PyCharm IDE
  9. Hello World Hello World in python is just a one

    liner. print "Hello, World!" Pretty neat. Isn't it?
  10. Hello World: Python 3 In python3 it's print("Hello, World!") Mind

    the parenthesis. In python3 print is a function.
  11. 1. Directly in the Python shell. Run python shell rst.

    ➜ python Python 2.7.12 (default, Nov 19 2016, 06:48:10) [GCC 5.4.0 20160609] on linux2 Type "help", "copyright", "credits" or "license" for more informa >>> Then >>> print "Hello World!" Hello World!
  12. 2. Standard approach Create a le hello_world.py with the code.

    print "Hello World!" Now run it with python. ➜ python hello_world.py Hello World!
  13. Compila on & Interpreta on Python is a dynamic language,

    and running it from the command line essentially triggers the following steps: 1. The source is compiled the rst time it is encountered (e.g., imported as a module or directly executed). This step generates the binary le, with a pyc or pyo extension depending on your system. 2. The interpreter reads the binary le and executes the instructions (opcodes) one at a time. From http://security.coverity.com/blog/2014/Nov/understanding-python-bytecode.html
  14. Incase you're from a C‐style language You need to be

    aware of few things in python. 1. No semicolon 2. No curly braces 3. Indentation is a part of syntax 4. Dynamically-typed language
  15. Pythonic code Looks something like this """ Generates Fibonacci series

    upto n """ def fib(n): a, b = 0, 1 while a < n: print a a, b = b, a+b fib(1000)
  16. Example 1: Prin ng and Comments # This prints Hello

    World! print "Hello World!" # This is a comment; single line comment """ And this is a multiline comment. As this could take more than one line of comments. Like this. """ print "Hello Again." Output: Hello World! Hello Again.
  17. Example 2: Prin ng More # Printing more texts print

    "Hello World!" print "Hello Again." print "We enjoy typing." print "Learning python is easy." print "And fun." print "Printing text is way easier." Output: Hello World! Hello Again. We enjoy typing. Learning python is easy. And fun. Printing text is way easier.
  18. Example 3: Prin ng more than just texts print "One

    + One =", 1 + 1 print "One - Two =", 1 - 2 print "Two * Five =", 1 * 5 print "Four / Two =", 4 / 2 print "Expression (12 * 5) - (2 ^ 3) + (1 / 2) =", ((12 * 5) - ( print "Seven is less than or equal to Six is", 7 <= 6 Output: One + One = 2 One - Two = -1 Two * Five = 5 Four / Two = 2 Expression (12 * 5) - (2 ^ 3) + (1 / 2) = 52 Seven is less than or equal to Six is False
  19. Example 4: Variables and Prin ng first_name = "Kabir" last_name

    = "Baidhya" dob = "July 30, 1992" home_town = "Kathmandu, Nepal" print "Hi! I am", first_name, last_name, "." print "I was born on", dob, "." print "I'm from", home_town, "." Output: Hi! I am Kabir Baidhya . I was born on July 30, 1992 . I'm from Kathmandu, Nepal .
  20. Example 5: Proper Forma ng first_name = "Kabir" last_name =

    "Baidhya" dob_month = "July" dob_day = 30 dob_year = 1992 difficulty = "easy" print "Hi! I am %s %s." % (first_name, last_name) print "I was born on %s %d, %d." % (dob_month, dob_day, dob_year) print "Python is %s to learn." % difficulty Output: Hi! I am Kabir Baidhya. I was born on July 30, 1992. Python is easy to learn.
  21. Example 6: User Input print "What is your name?", #

    This would take input from the user # and store it in a variable. name = raw_input() print "Hi! %s. \nIt's nice to meet you." % (name) print "Hope you're doing good." Output: What is your name? Kabir Hi! Kabir. It's nice to meet you. Hope you're doing good.
  22. Buit‐in Data types Numeric: int, oat, long Boolean: bool Sequences:

    str, list, tuple, bytes Mappings: dict Sets: set, frozen set Read more https://en.wikibooks.org/wiki/Python_Programming/Data_Typ es
  23. Immutable & Mutable types 1. Immutable types int, oat, long,

    tuple, byetes, frozen set, etc. 2. Mutable types list, dict, set, etc.
  24. Example 7: Basic data types an_integer = 6 a_floating_point =

    17.60 a_boolean = True a_string = "Foo" print "Integer value = %d" % an_integer print "Float value = %f" % a_floating_point print "Boolean value = %r" % a_boolean print "String value = %s" % a_string Output: Integer value = 6 Float value = 17.600000 Boolean value = True String value = Foo
  25. Example 8: Lists fruits = ['Banana', 'Apple', 'Lime'] numbers =

    [1, 2, 3, 4, 5, 6, 7, 8] # This is called list comprehension even_numbers = [x for x in numbers if x % 2 == 0] print "Numbers: %s" % numbers print "Even Numbers: %s" % even_numbers print "Fruits: %s, %s and %s" % (fruits[0], fruits[1], fruits[ Output: Numbers: [1, 2, 3, 4, 5, 6, 7, 8] Even Numbers: [2, 4, 6, 8] Fruits: Banana, Apple and Lime
  26. Example 9: Dic onaries data = { "name": "Kabir Baidhya",

    "dob": "July 30, 1992", "home_town": "Kathmandu, Nepal" } print "Hi! I am %s." % data["name"] print "I was born on %s." % data["dob"] print "I'm from %s." % data["home_town"] Output: Hi! I am Kabir Baidhya. I was born on July 30, 1992. I'm from Kathmandu, Nepal.