Python Introduction

I started this section by following this video to "Learn Python in 1 Hour", but then immediately got distracted by Python's potential and went down a rabbit hole.[1]

Also, if you want some real data to mess with[2], you can use Kaggle to access a TON of CSV files on a range of topics.

Key Features and Definitions in Python

  1. Case-sensitive
    1. "True" represents the Boolean true value, and "true" is just a string
  2. Object-oriented
    1. Bundles attributes and functions to individual units (objects)
    2. Classes identify which attributes are used to define a type of object
      1. e.g., class Hognose:
    3. Methods are used by Classes to define or represent the specific attributes
      1. The method def __init__(self,...) defines attributes for the class, and then to further define the attributes.
        1. e.g., def __init__(self, name, age, length, ...) # Identifies the attributes name, age, length, etc. to define the class
          self.age = int(years) # Identifies the age for the Hognose class as the "years" variable converted to an integer.
      2. The method def __repr__(self):... provides an "official" string representation of the object
        1. e.g., def __repr__(self): # Initiates representation.
          return (f"Hognose(name='{self.name}', age={self.age},...) # Returns
  3. Primitive data types
    1. Strings
      1. Unformatted, considered text
        1. "12" is a string, and cannot be added to or subtracted from
      2. Special note
        1. F-Strings are a special kind of formatting for strings, introduced in Python 3.6, which allow you to easily input variables into a string.
        2. Variables are identified using curly[3] brackets
        3. e.g. greeting = f'Hello, my name is {name} and I am {age} years old.'
    2. Integers
      1. Whole numbers that can be manipulated with equations
      2. 1+1 will equate to 2
      3. Can also convert strings to integers with int() (see example below)
        1. birth_year = input("Enter your birth year (YYYY): ") # Accepts the birth year from a user as a string
        2. int(birth_year) # Converts the "birth_year" variable from a string to an integer
    3. Float
      1. "Floating point number", which are rational numbers that usually end in decimal figures
      2. e.g., 3.14 or 0.5
    4. Boolean
      1. Simple True and False or 1 and 0
      2. Boolean values[4]
    5. Conversion Functions
      1. Strings, integers, float, and Boolean data types all have associated functions that convert values from one type to another
      2. The functions are str(), int(), float(), and bool()
        1. For example, int(age) will convert the "age" variable into an integer
      3. Function bool() evaluates any value as "True" or "False"
        1. True in this case effectively refer to any non-null[5] value
        2. Even -1 returns True
  4. Non-primitive data types (non-comprehensive)
    1. Lists
      1. Holds a large number of items of any data type
      2. Highly flexible; items can be added or removed
    2. Arrays
      1. Not natively supported in Python
      2. Like lists, but more efficient when handling large data sets of the same type
    3. Tuples
      1. Not a sex thing[6], but is an ordered list of values.
      2. There can be duplicates, and they are not changeable once created
    4. Dictionary
      1. A list of key-value pairs.
        1. The keys must be unique, but the values do not
          1. e.g., dictionary = {'a': 1, 'b': 2, 'c': 1}
          2. a, b, and c are the unique keys, followed by their values
  5. Style guide
    1. PEP (Python Enhancement Proposals)
      1. PEP 8 – Style Guide for Python Code | peps.python.org
      2. This is a style guide with a bunch of specific recommendations
    2. CapWord Convention
      1. When stringing a bunch of words together, capitalize the first letter of each word
        1. e.g. BigHairySpider
      2. Typically reserved for class names
        1. NOTE: Sometimes IDEs like PyCharm are too smart for their own good, and will read words like "Hognose" as a violation of this convention (it expects "HogNose")
        2. In PyCharm, if you're working with a term frequently, this can be resolved by adding it to PyCharm's dictionary
          1. Right-click the alert, select "Show Quick-Fixes", and then "Save 'Hognose' to dictionary"
    3. snake_case convention
      1. String words together with underscores _ instead of capital letters
        1. e.g., big_hairy_spider
      2. Typically used for functions, methods, and variables
    4. Commenting
      1. Comments should be written as a sentence, begin with a capital letter, end with a period, and are identified with a pound and single space (# ) at the start
      2. Block comments begin at the start of a line
        1. e.g., # This is a comment.
      3. Inline comments should be used sparingly
        1. Don't state the obvious
        2. e.g., x = y + 1 # Compensate for image border.
          1. Where y is the true edge of the image, and x is the image edge with 1 pixel buffer-zone for a stylized border.
  6. Objects
    1. Any variable can be an object, and can have methods run against it
      1. The changes do not impact the original variable; they create a new variable in memory.
        1. e.g., snake.upper() d
      2. e.g., let's say we have the variable snake = "my best friend hoggy the hognose"; we can use methods to manipulate the value.
        1. find: snake.find("Hog") to find if the string "Hog" exists in the value
          1. If it exists, the output is the position of the first character, starting at 0
          2. If it doesn't exist, the output is -1
        2. capitalize: snake.capitalize() would capitalize the first letter of the string
          1. Printing this gives us "My best friend..." instead of "my best friend..."
        3. replace: snake.replace(x,y)' to replace vale x with value y
          1. snake.replace('friend','buddy') would result in "my best buddy..."

Basic/Imporant Commands/tools

  1. print()
    1. Print the contents of the parenthesis to the console
  2. variable = value
    1. Declare a variable
    2. Used in code without quotes
      3. For example, let's say nice = 69
      4. print(nice) would print the value of nice, 69
      5. print("nice") would print the string "nice" (but without the quotes)
  3. datetime
    1. datetime — Basic date and time types — Python 3.12.2 documentation
    2. strptime() converts a string into a datetime object, and strftime() converts a datetime object into a string

Hognose Census Project

Let's say we have a CSV list of hognose snakes with a bunch of data. The CSV was created by a human for humans, and has pretty long headers to help human operators input correct information.

We want to ingest the data from the CSV file, converting strings into their most appropriate value type (Boolean, integer, datetime, etc.) for maximum utility.

For this project, I'm going to over-comment to help the tl;drs out there.

  1. Or hognose hole, if you will. ↩︎

  2. And don't want to go Google Dorking and possibly uncover PII... ↩︎

  3. hooray-yay.gif ↩︎

  4. Boolean data type - Wikipedia ↩︎

  5. Null being the number 0, boolean False, the string "None", or an empty value ↩︎

  6. Probably. ↩︎