nicklope / u4_lesson_python_intro

In this lesson we'll discuss why Python 3 is a popular and valuable programming language in the world today. We'll also be covering basic syntax in relation to JavaScript syntax, and how to set up a python environment.

Introduction To Python 3

Overview

In this lesson we'll discuss why Python 3 is a popular and valuable programming language in the world today. We'll also be covering basic syntax in relation to JavaScript syntax, and how to set up a python environment.

Getting Started

We'll start by installing Python 3:

Mac Users

brew install python3

python3 --version

WSL

sudo apt update && sudo apt upgrade

sudo apt install python3 python3-pip ipython3

python3 --version

VsCode Extensions

Install the following extension for vsCode:

• Python

Open the main.py file, vsCode will prompt you to install a few things such as:

• Linter, select pylint
• Formatter, select autopep

The python language extension gives us better support for the python language such as, intellisense, autocomplete and linting.

What Is Python

From Python.org:

Python is an interpreted, object-oriented, high-level programming language with dynamic semantics. Its high-level built in data structures, combined with dynamic typing and dynamic binding, make it very attractive for Rapid Application Development, as well as for use as a scripting or glue language to connect existing components together. Python's simple, easy to learn syntax emphasizes readability and therefore reduces the cost of program maintenance. Python supports modules and packages, which encourages program modularity and code reuse. The Python interpreter and the extensive standard library are available in source or binary form without charge for all major platforms, and can be freely distributed.

Take a few minutes to read this article about why Python has become so popular:

Why Is Python Popular

Python has become popular in the world of data science because of it's ability to easliy parse various types of files and data formats, although not the fastest, it's syntactically easy to understand as it looks almost like plain english. It's a human readable programming language.

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Python Basics and Syntax

Data Types

Python has similar data types to javascript, everything from numbers to objects. However some data types in python have a different name, we'll see more of that at another time. In the meantime, here's a list of python data types and their corresponding javascript equal:

Type	Python Type	Js Type	Mutable
string	"string" or 'string'	"string" or 'string'	Yes
integer	32	32	Yes
float	3.55	3.55	yes
object	{"myKey": "myValue"} => Dictionary	{myKey:"myValue"}	Yes
array	["Hello","World"] => List	["Hello", "World"]	Yes
null	None	null	No
tuple	('My','Tuple')	N/A	No
boolean	True False	true false	yes
undefined	N/A	undefined	no

Variables

In javascript, we declare variables in camelCase in Python, we use snake_case for multiple words or lowercase for a single word. We store the value for the variable using the = sign.

Let's practice defining some variables in the main.py file, set each variable to its corresponding type, Example: some_var = 'Hi'

• Create a variable for your name, string.
• Create a variable for number of items, integer.
• Create a variable for max sum, integer.
• Create a variable for completed, boolean.
• Create a variable for items, none.
• Create a variable for numbers, list.
• Create a variable for unique items, dictionary.

Comments

To create comments in python, we use the # symbol at the beginning of the line, practice writing some comments in main.py:

• Write a comment that says Hello Big Blue World, each word should be on it's own line.

Printing Results To The Console

To print results to the console, we use the print function like so: print("My Message")

Practice logging things to the console, we'll only be utilizing strings so put everything in a set of quotes '':

• Log your age to the console.
• Log your name to the console.

Execute the file by running python3 main.py in your terminal in the intro-to-python directory.

Arithmetic Operators

Python has basic math operators built in just like many other programming languages. Here's a list of those operators:

Operator	Operation
+	addition
-	subtraction
*	multiplication
/	division
%	modulus => returns the remainder
**	exponentiation
+=	plus equals

Useful String Methods

• '{var}'.format(var='Cat') => Works like template literals
• '' + '' => String Concatenation

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You Do

Let's do some basic math problems, work in the main.py file you'll be performing the following and printing them. Check your work by running the main.py file => python3 main.py:

• Create a variable to store the sum of 10 plus 10.
• Create a variable to store the result of 23 minus 43.
• Create a variable to show the remainder of 4.
• Create a variable for the result of 2 times 3.
• Create a variable to store the result of 10 divided by 5.
• Create a variable to store the value of 3 to the 4th power.
• Create a variable to store any number, using the plus equals operator add 10 to that variable

Recap

As you can see, python has many similarities to other programming languages. A lot of what you've learned in javascript can translate to python! Certain data types go by different names and variables are set up slightly different.

Resources

• Python 3 Language Reference Docs
• Article: What is Python Used For? 7 Major Uses