agenda.txt

Lesson #8 (Video 10): Python Dictionaries

Dictionaries:

    Define a dictionary by using {} curly braces
    Example:
        myDict = {'Hi': 'Hello', 'Bye': 'See you later'}

    To access the value that corresponds with a key, index the dictionary
    Example:
        value = myDict['Hi']
        print(value)
            > Hello

    To delete a key, use the del keyword
    Example:
        del myDict['Hi']

    To add a key or update the value of the key, use the following syntax:
    Example:
        myDict['Yes'] = 'Yeah' #Adding a new key
        myDict['Hi'] = 'Hola!' #Updating an existing key

    To get a list of keys and values, follow these steps
    Example:
        print(myDict.keys())
        print(myDict.values())

    Dictionaries are amazing, but they have a few restrictions:

        1. The keys should be immutable, or unchangeable
        2. Duplicate keys are not allowed. Each key overrides the value of the previous key.

    ADVANCED:
    
        for key, value in myDict.items():
            print("Another way of saying", key, "is", value)











Try and Expect:

Errors can be confusing, but we can catch them and handle them.

Under "Try", we put the actions we want to do (e.g. Print something or add 2 integers).

If those specific actions give us an error, the "except" keyword lets Python
know that it shouldn't throw an error, as we ourselves will handle it.

Under "Except", we put the actions that should be done if the "try" actions give an error.

The 'Finally" keyword is a keyword that allows an action to be done whether or not we
get an error.








Lesson #10: Functions

Functions are very fundamental and useful aspects of programming. They take the role of tools that help
develop strong and clean code.

print(), round(), and int() are just some examples of Python's built-in functions.

Using the "def" keyword, we can define our own functions. This way, we can reduce the 
repetition of code and well as improve its readablity.

Important definitions to know:

Function - A piece of code that performs an action when called.

Parameter(s) - The place where the value(s) must be passed in a function

Argument(s) - The actual value(s) being plugged into the function.

Return Value - The value a function outputs after doing a certain action. A return value
is not required in some functions.








Extra Must-Know components of Python.

1. List Comprehension:

Easy one-line way to make a list.

Syntax:


[i for i in range(5)]`
[i for i in range(5) if i > 2]
[i if i > 2 else None for i in range(5)]


2. lambda

Anonymous one-time use function.

3. filter

Filters out certain elements from a sequence.

Filter this list to only contain animals names that have 5 or more letters:

animals = [cat, dog, lion, fish, llama, giraffe, tiger, owl]






Classes And Objects:

    Classes:
        - In Python, a class is like a blueprint that defines certain properties of an object.
        - A class can be seen as a cookie cutter, an object that defines the shape of a cookie.

        Syntax:
            - The Syntax of creating a class is class <name of the class>. For example:

                class Vehicle:
                    <properties of the object>
        - It is always a good practice to define an __init__ method to store attributes of a class.
        - Inside classses, we can define attributes or methods that allow an object to
        perform certain tasks and hold data.

            The Syntax for attributes is similar to that of a normal variable in python.
            The Syntax for methods is similar to that of a normal function in python.

    Objects:

    Syntax:

        car = Vehicle(<arguments coresponding with the parameters in the __init__ function>)

        - The attributes and methods of an object can be called upon.