New functions can be created with the keyword def, as such:

```python
def sub(x, y):
   return x - y

def add(x, y):
   return x + y

def square(x):
    return x ** 2
```
 


Defining Functions in Python 

Functions are displayed and written in the following format:

- For one argument: functionname(argument)
- For two arguments: functionname(argument1, argument2)
- For three arguments: functionname(argument1, argument2, argument3)
- *And so forth 

Format of Functions in Python

The terms input and argument are often used interchangeably to refer to function arguments. However, the term "input" can also refer to the input() function. 

"Argument" will universally refer to information that is passed into a function as such: function(argument) 

Inputs vs Arguments in Python

Python comes with a host of built-in functions. Here are some examples:
- print()
- input()
- id()
- range()
- abs()
- bin()
- bool()
- len()
- round()
- pow(x,y,z)
- chr(i)
- slice()
- ord()
- hex()
- oct()
- int()
- float()
- str()
- open()



Built-In Functions in Python

In Python, function parameters refer to the variables that are listed within a function definition. For example, in the function rotate(x, y), the parameters are x and y.

Function Parameters in Python

Which of the following are true about functions in Python? (choose all that apply)

Lambdas are shorthand function definitions. A lambda function is a small anonymous function. A lambda function can take any number of arguments, but can only have one expression. The syntax is, lambda arguments : expression. For instance,

```python
func = lambda x, y : x + y
```

defines a Python function that takes two arguments (which must support the + operator) and returns their sum/concatenation.

Lambdas in Python

Example of the square function:
- ```square(4)``` --> 16

Example of the subtraction function:
- ```sub(6, 4)``` --> 2

Example of the square function in a multidimensional problem:
- ```sub(square(3), square(4))``` --> -7 

Example of the print function:
- ```print(3)``` --> *Integer 3 will actually display on output screen. 

Examples of Python Arithmetic Functions 

A Python generator is a special type of function that returns a lazy iterator. Instead of computing and storing all values in memory at once, a generator produces one value at a time using the `yield` keyword, pausing its execution state between calls. This memory-efficient approach makes generators highly effective for processing large datasets, such as in deep learning data loaders where they iteratively yield a single data batch without loading the entire dataset into memory.

Python Generator

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. 

University of Michigan - Ann Arbor

Google

- 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

Reference of Foundations of Large Language Models Course

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. 

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

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 

- 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 

- 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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