Variables and Data Types in Python

Study Notes

Variables:
- A name given to a value
- Assigned using the assignment operator (=)
- Can be reassigned
Data Types:
- Integer (int): whole numbers, e.g. 1, 2, 3, etc.
- Float (float): decimal numbers, e.g. 3.14, -0.5, etc.
- String (str): sequence of characters, e.g. "hello", 'hello', etc.
- Boolean (bool): true or false values
- NoneType (None): represents the absence of a value
Type Conversion:
- Using built-in functions, e.g. int(), float(), str(), etc.
- Implicit conversion, e.g. when using operators

Arithmetic Operators:
- Addition: a + b
- Subtraction: a - b
- Multiplication: a * b
- Division: a / b
- Modulus: a % b
Comparison Operators:
- Equal: a == b
- Not Equal: a != b
- Greater Than: a > b
- Less Than: a < b
- Greater Than or Equal: a >= b
- Less Than or Equal: a <= b
Logical Operators:
- And: a and b
- Or: a or b
- Not: not a
Control Structures:
- If-Else Statements:
  - If condition: executes if condition is true
  - Else clause: executes if condition is false
- For Loops:
  - Iterates over a sequence (e.g. list, string)
  - Executes a block of code for each item
- While Loops:
  - Executes a block of code while a condition is true

Functions:
- A block of code that can be executed multiple times
- Defined using the def keyword
- Can take arguments and return values
Function Arguments:
- Positional Arguments: passed in the order they are defined
- Keyword Arguments: passed using the parameter name
Modules:
- A collection of related functions and variables
- Imported using the import keyword
- Examples: math, statistics, time, etc.

Lists:
- A collection of items that can be changed
- Defined using square brackets []
- Items can be added, removed, or modified
Tuples:
- A collection of items that cannot be changed
- Defined using parentheses ()
- Items cannot be added, removed, or modified
Indexing and Slicing:
- Accessing individual items using their index (0-based)
- Slicing: accessing a subset of items using a range of indices
List Methods:
- append(): adds an item to the end of the list
- insert(): adds an item at a specific position
- remove(): removes the first occurrence of an item
- sort(): sorts the list in ascending order

A variable is a name given to a value, which can be assigned using the assignment operator (=) and reassigned as needed.
There are five basic data types in programming:
- Integer (int), which represents whole numbers, such as 1, 2, 3, etc.
- Float (float), which represents decimal numbers, such as 3.14, -0.5, etc.
- String (str), which is a sequence of characters, such as "hello", 'hello', etc.
- Boolean (bool), which can have a value of either true or false.
- NoneType (None), which represents the absence of a value.

Lists:
- Ordered collections of items, allowing for modification and duplicate values.
- Indexing starts at 0, making it easy to access specific elements.
- Example: my_list = [1, 2, 3, 4, 5]
Tuples:
- Ordered, immutable collections of items, preventing modification after creation.
- Like lists, tuples can contain duplicates, but indexing starts at 0.
- Example: my_tuple = (1, 2, 3, 4, 5)
Dictionaries:
- Unordered collections of key-value pairs, allowing for modification.
- Keys must be unique, preventing duplicates.
- Example: my_dict = {'name': 'John', 'age': 30}
Sets:
- Unordered collections of unique items, allowing for modification.
- Automatically removes duplicates, ensuring a unique set of items.
- Example: my_set = {1, 2, 3, 4, 5}

For Loop:
- Used for iterating over sequences (strings, lists, tuples, etc.).
- The syntax is for variable in iterable:, making it easy to iterate over collections.
- Example: fruits = ['apple', 'banana', 'cherry']; for fruit in fruits: print(fruit)
While Loop:
- Used for iterating as long as a condition is true.
- The syntax is while condition:, allowing for customized looping.
- Example: i = 0; while i < 5: print(i); i += 1

If Statement:
- Used for making decisions based on conditions.
- The syntax is if condition:, allowing for simple decision-making.
- Example: x = 5; if x > 10: print('x is greater than 10')
If-Else Statement:
- Used for making decisions based on conditions with an alternative option.
- The syntax is if condition: else:, providing a default response if the condition is false.
- Example: x = 5; if x > 10: print('x is greater than 10'); else: print('x is less than or equal to 10')