Skip to main content

Notes - Sun 12/20/20

12/20/20

Starting! My 2 week goal is to create the game Snake in Python. So I can kickstart my new game dev studio.

I got overwhelmed with options for editors and went with Visual Studio Code ("VS Code") which was recommended by the jwaz nerd chat. Mu will be my backup as I'm currently not sure how VSCode will work with the Pybadge or how to get a REPL working.

Below is an example code we were to use to teach us how to save a .py file in Sublime or another text editor.

print('hello world')

Jupyter Notebooks Notes

How to open files

I can open Jupyter notebooks through the actual Jupyter Lab program by running jupyter-lab in the CLI. That will open something up in the browser which I can navigate around in. Or I can open the notebooks up in VSCode which I like since the one app can open up my code, my own notebooks, and the notebooks from the class.

How to create new notebooks in VSCode

Ctrl+Shift+P then type in "Create new blank Jupyter notebook

Git Notes

Once I start getting more complicated projects, I'll want to keep backups or setup "source code management" (SCM) to track changes to my code. Git helps to do this and is seperate from Github. Git can be a local tool and I can back up my projects and code to my Nextcloud server if I want. Github is a tool that uses git but is onilne and I could share projects with others among other features.

As of 12/20/20. I haven't setup git yet. I should probably do so in the future.

Some helpful links:

Types of Data

  • Integers (int) = Whole numbers - 3, 300, 200
  • Floating Point (float) = Numbers with decimal places - 2.3, 4.6, 100.0
  • Strings (str) = Ordered sequence of characters so just text - "hello", "Sammy", "2000"
  • Lists (list) = Ordered sequence of objects so text, Integers, or Floating Points could go in here - [10,"hello",200.3]
  • Dictionaries (dict) = Unordered Key:value pairs (more info coming later; currently doesn't make sense to me) - {"mykey":"value", "name":"Anson"}
  • Tuples (tup) = It's said like "too-pul-es". It's a sequence of objects that and the order can't be changed aka immutable (more info coming). - (10,"hello",200.3)
  • Sets (set) = Unordered collection of unique objects {"a","b"}
  • Booleans (bool) = Logical value indicating True or False

   

Note that:

Integers do not have decimals.

A Floating Point number can display digits past the decimal place. A floating point number does not represent EXACT values, just a close/increasingly better approximation of a value. For example 1/3 doesn't mean the value is 0.3, 0.33, or 0.333. It's how the computer holds the approximate value. So 0.1+0.2-0.3 doesn't equate to 0.0. Just a value really close to 0. Click this link for more info.

Numbers in Python

There's 2 main types of numbers as listed above: integers and floating point.

Python can be used as a straight up calculator. I can literally type in 2+2 and run the code to get a value.

Mod operator %

You could also have python output a "Mod operator" or a "Modulo".

Let's say you wanted to do 7/4. You would say that 4 goes into 7 one time with a remainder of 3. So the mod operator will output the remainder. In this way, you can quickly see if a number is easily divisible by another number.

In the previous example, we had a remainder of 3. So 4 does not go into 7 easily. But 5 goes into 50 cleanly. We would expect the remainder to be 0.

To use the mod operator, you'd use the % sign. X % Y

You can also use the mod operator to check if a number is even or odd. For example if you have a variable that is a number and you're not sure if it's even or odd. If I get a remainder from the mod, then it's odd. If I get 0, then it's even.

23 is odd. 20 is even.

Exponents **

I can do Exponents by doing x ** y.

Order of Operations

Remember PEMDAS for order of operations - parenthesis, exponents, multiplication/division, addition/subtraction

If I just type in normal formula. Python will follow the order of operations. If I want to control the order Python does the math in, I will have to use parenthesis.

Variable Assignments

We could assign the above data types a variable name.

Names can't:

  • Start with a number
  • No spaces - need to use underscore _ instead
  • No special symbols besides _ (Python will complain if the special symbols are used)

Names should:

  • Be in lowercase as a best practice
  • Avoid keywords as variable names such as list or str (the editor should highlight those keywords a different color)

Python uses dynamic typing. So variable names can be reassigned. The below can happen. In other langauges such as C++, this can't be done. Once the integer of "my_dogs" is assigned, it stays that way.

  • my_dogs = 1
  • ``my_dogs = ["Armani"]

Dynamic Typing Pros:

  • easy to work with
  • saves time since you don't have to assign a data type. So for example, in the above example, C++ wants to see an integer data type assignment. int my_dogs=1

Dynamic Typing Cons:

  • Easy to have unexpected data types could cause bugs

How to determine data type using Type()

Let's say we don't know what kind of data "a" is and we want to find out. We would use type(a)

  • type() could help find those errors (discussed below)

I ran the code below in a Jupyter notebook.

a = 5

type(a)

a = 30.1

type(a)

Syntax Highlighting and variables

Note that above we can see that type() shows that my data was an integer then a floating point number. We can also see that "type" is highlighted in an aqua green color. That shows that its a python keyword. So we shouldn't name a variable "type". If I accidently make a variable named "type", I can undo this by restarting the variable. In VSCode, the symbol is the little green circular arrow.

Variable name example

Let's say I want to calculate my taxes.

  • Income = 100
  • Tax Rate = 0.1
my_income = 100

tax_rate = 0.1

my_taxes = my_income * tax_rate

Then run my_taxes and the answer should be 10.0

Back to top