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README.md
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# Python Fundamentals
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### Learning Objectives
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***Students Will Be Able To...***
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* Create a variable in python
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* Assign the different data structures to variables
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* Write python statements using control flow
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* Write python statements using loops and iteration
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---
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### Context
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* The fundamentals of programming translate throughout every language
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* Like learning any new language we're going to start with the basics and build up
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* If you wanted to learn English you wouldn't start by reading a novel, but with the alphabet
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### Variables
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* Variables are a way to store and save data for use
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* This is called `assignment`. You are assigning a value to a variable
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* Declaring Variables
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* Cannot start with a number
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* Cannot declare with special characters
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* Written in snake case
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* Open up Python in the terminal
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```python
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name = "Jason"
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fav_num = 8
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turtles = ["Raph", "Leo", "Mickey", "Donny"]
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```
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### Data Types
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* Now you may have noticed that variables can hold different `types` of values
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* These are called `Data Types` and python3 has [many built-in types](https://docs.python.org/3/library/stdtypes.htm)
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* [Strings](https://docs.python.org/3/library/stdtypes.html#str)
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* Sequence of 0 or more characters(a-z, A-Z, 0-9, !,@,#, ect).
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* python type `str()` or with the literal `''` or `""`
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* [methods to know](https://docs.python.org/3/library/stdtypes.html#string-methods)
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* `.format()` [https://pyformat.info/](More info)
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* `.isdigit()`, `islower()`, `isupper()`, check to see if the string is a digit and so on. There are many more like these
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* `.lower()`, `.upper()` changed the string to lower and up case
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* `.split()` changes the string to a list based around the character[s] given
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* [Numbers](https://docs.python.org/3/library/stdtypes.html#numeric-types-int-float-complex)
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* [Floats](https://docs.python.org/3/library/functions.html#float)
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* decimals
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* python type `float()` or with the literal `23.3`
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* methods to know
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* `is_integer()` Return `True` if the float a whole number, and `False` otherwise
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* [Integers](https://docs.python.org/3/library/functions.html#int)
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* whole number
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* python type `int()` or with the literal '4'
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* [Lists](https://docs.python.org/3/library/stdtypes.html#lists)
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* Ordered sequence of items
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* python type `list()` or the literal `['a', 'b', 'c']`
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* methods to know
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* `.append()` adds a item to a list
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* `.pop()` removes and returns the last item from the list
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* [Dictionary](https://docs.python.org/3/library/stdtypes.html#dict)
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* Collections of key, value pairs
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* python type `dict()` or the literal `{'key':'value'}`
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* methods to know
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* `.get()` return the value of a give key, or a default value if its not found
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* `.values()` returns a `list` of values in the Dictionary
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* `.keys()` returns a `list` of keys in the Dictionary
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* [Booleans](https://docs.python.org/3/library/stdtypes.html#boolean-values)
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* Represents something that is `True` or `False`
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* python type `bool()` or the literal `True` or `False`
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* [Range](https://docs.python.org/3/library/stdtypes.html#range)
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* `Range()` is a special type that represents range of numbers
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* [None](https://docs.python.org/3/library/stdtypes.html#the-null-object)
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* nothing, nothing at all
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* python type ... there is one way, the literal way `None`
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### Notable built in functions
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* `len()` return the length of the given *sequence*
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* `help()` shows help documentation of the given object
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* `dir()` show the available methods of the give object
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#### Math Operators
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All math operators can be done on both floats and ints
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Python comes with the following symbols for mathematical operators.
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* `+` add
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* `-` subtract
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* `*` multiplication
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* `\` division
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* `\\` floor divided, always returns a whole number
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* `%` modulo: finds the remainder after division
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* The language also supports PEMDAS
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* `5+(50+5)`
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#### Comparison Operators
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* `==` equality
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* `!=` not equal
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* `<` less then
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* `<=` less then or equal to
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* `>` greater then
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* `>=` greater then or equal to
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#### Control Flow
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* Now we have reached `if/else` statements
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* If an expression you passed in is `True` do something
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* `else` do something `else`
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```python
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if expression == true:
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run code
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if name == "Jason":
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print("That is an awesome name")
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else:
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print("You should get a different name")
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if number > 100:
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print("That's a big number")
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elif number > 50 && number < 100:
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print("That's a medium number")
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else:
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print("Your number is puny")
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```
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* Things to note
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* Put a colon after the expression you want to evaluate to start the `if` body
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* `if` to `elif` to `else`
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* indents show what code is part of the body of the statement and where it ends
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#### Lists and Indexing
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* What if you wanted to store more data.
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* Can be assigned to variables
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* Can hold different data types at once
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* The values are indexed for us starting at zero
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```python
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my_list = ["Jason", "Anna Kendrick", 2015, True]
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my_list[0] == "Jason" # True
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my_list[2] == 2016 # False
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```
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* Just a heads up indexing through a list is similar to indexing with strings.
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* the value at index zero will be the first element in the list, or the first letter in a string
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#### Functions and Statements
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* We declare our functions with the word `def` for define
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* Functions follow the same naming principles as declaring variables
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* Snake case
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* Do not start with numbers or special characters
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* Remember how we used white space to organize our code with if/else statements. Well that idea holds true everywhere in Python
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```python
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def my_name():
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return "My name is Jason"
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```
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* Functions allow us to build code that is reusable
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* This follows the concept of **DRY - Don't Repeat Yourself**
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* Functions can also take arguments. These allow our functions to be more dynamic
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```python
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def my_name(name):
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return "My name is " + name
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```
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* When there is no `return` statement, the function *implicitly* returns `None`
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### `for` loops
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`for` loops *iterate* over a *sequence*. There are 2 parts to a `for` loop, the *statement* and the *body*. The *statement* tells the loop what to *iterate* over and *assigns* the loop variable. The body tells python what to do in each iteration. Before each iteration the loop variable is assigned to the next value in the *sequence*, in oder from the zero index to the last item.
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```python
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teachers = ['billy', 'tom', 'jason', 'jeff']
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for teacher in teachers:
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print( teacher.capitalize() )
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```
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In this loop we *iterate* over each teacher in the loop and print there name capitalized.
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### `while` loops
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Unlike `for` loops, `while` are not bound to a sequence and can continue for ever.
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like a `for` loop, `while` loops have 2 parts, an *statement* and a body.
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```python
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num = input('Please enter a whole number: ')
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while not num.isdigit():
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print('Not a whole number!')
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num = input('Please enter a whole number: ')
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```
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### loop control
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There are 2 ways can control what loops. They both with `for` and `while` loops in the same way.
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* [`break`](https://docs.python.org/3/reference/simple_stmts.html#break)
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The `break` *statement* stops loop and allows python to move on to the rest of the script. If you are using a `while` loop, you should have a break *statement* to stop the loop.
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```python
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count = 1
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while True:
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count *= count
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if count > 100: break
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```
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* [`continue`](https://docs.python.org/3/reference/simple_stmts.html#continue)
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The `continue` *statement* skips to the next iteration of the loop. Generally, `continue` statement are at the top of the loop body.
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```python
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for num in range(100):
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if num%10 != 0: continue
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print(num)
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```
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