A variable is where data values can be stored. Another way to say this is that a value can be referred to by its respective variable. Variables do not need to be declared with any particular type, and can even change type after they have been set.

Variables in Python

Values can be classified into different classes, known as data types:
- Integer (int) - 1, 4, 7, 24, 578, etc.
- Float (float) - 2.2, 2.59, 3.14159, etc.
- String (str) - *Any combination of characters in quotes
- List (list) - An ordered, mutable collection of items
- Tuple (tuple) - An ordered, immutable collection of items
- Dictionary (dict) - An unordered collection of data with keys and values
- Boolean (bool) - True or False
 
The terms "data type" and "class" are often used interchangeably.

Data Types in Python

Use the equal sign ("=") with the variable name on the left and the value on the right. 

Examples:
- car_model = "Ford Taurus"
- Total_Cost = 400
- n = 18

Note that the equal sign does not mean "equal to" in this case. It should be read as "(Variable) refers to (Value)." For example, "n refers to 18." 

Setting Variables in Python 

- Expressions are any combination of data types to be evaluated. Evaluating an expression results in values/objects. Expressions can also be evaluated into or set to values. 
- Asking Python to print an expression will result in the interpreter attempting to evaluate the expression and display the result

Expressions in Python 

Scope determines where a variable can be accessed. The two common Scopes are Local scope and Global scope.

Variables in Local scope are called local variables and these variables are defined inside a function. Local variables can only be accessed inside that function. Similarly, variables defined inside a loop of a function can only be accessed inside that loop. To use those variables outside of the loop in the rest of the function, they must be defined before the loop starts. 

Variables in Global scope are called global variables and these are defined outside functions. Global variables are accessible anywhere in the Python module.

Scope in Python

A value is any thing in the form of a number, string, character, etc. that can be manipulated. Values can also be referred to as objects. 

University of Michigan - Ann Arbor

- Values 
- Operators & Operands
- Functions
- Statements
- Expressions
- Debugging
- Classes and Objects
- Data Structures

Python Programming Language Foundational Concepts 

https://runestone.academy/runestone/books/published/fopp/index.html

Runestone: Foundations of Python Programming

Values in Python

Operators are things that represent computational processes in Python. These include +, -, *, **, //, %, and /. 
- "+" = Addition
- "-" = Subtraction
- "*" = Multiplication

- "**" = Exponent
- "//" = Divide, but only include whole number in result
- "%" = Modulo, which only displays remainder of operands 

Operands are the values being acted on by the operator. 

Operators & Operands in Python

Function can be thought of as devices that take in material, perform a specified operation on the taken-in material, then output a resulting object. 

Inputs are referred to as arguments 
End result is referred to as output or return value. 

Functions in Python

A statement is any line of instruction that the Python interpreter can potentially execute. 

Types of statements include but are not limited to:
- Variable assignment statements 
- while statements
- for statements
- if statements
- import statements 

Statements in Python 

- General Tips & Tricks
- Common Syntax Errors
- Error types
- Error Messages

Debugging in Python

A Class allows us to group together data and functions. It provides a template which can be instantiated to create objects. Classes and Objects help improve readability and allow code reuse. 

Classes are most often used in Object Oriented Programming, as they allow programmers to bundle sets of functions and data together. 

Python Classes and Objects

Data structures facilitate the organization of data in computer memory in an efficient manner which further support faster and more flexible data manipulations.


The python interpreter offers the following built-in data structures:


- List
- Set
- Tuple
- Dictionary


Data Structures in Python

https://www.geeksforgeeks.org/vectorization-in-python/

Vectorization in python

Vectorization is a computational technique used to replace explicit, element-by-element loops (such as Python for-loops) with optimized operations on entire data structures simultaneously. In machine learning, vectorization leverages highly optimized linear algebra libraries to perform mathematical operations—like calculating the elementwise sum of vectors or processing whole minibatches of examples—at once. This approach dramatically reduces execution time by yielding order-of-magnitude speedups, simplifies code, reduces the potential for bugs, and increases portability by offloading mathematics to underlying libraries.

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