Python Basic Part II: Snake Logic

Posted by Christopher Kalfas on April 24, 2020

Hello, to my loyal followers. As promised, here is the follow up to last week’s blog on Python Basics. In this entry, I’m going to cover arithmetic, string methods, comparisons, booleans, and conditionals.

In case you must Part I, here is the link. Python Basics: Part I

ARITHMETIC

Python’s round method takes the decimal and rounds down or up to the nearest whole number.

  • Example: round(2.4) returns 2
  • Example: round(2.6) returns 3

Python follows standard Order of Operation - PEMDAS. For those who don’t remember what means:

  • “Please, excuse my dear aunt Sally.”
  • Parenthesis - Exponents -Multiplication - Add - Subtract

Integers & Floats - Python allows data type coercion using the integer, float, and string methods

  • Example: int("7") returns 7

  • Example: int(7.8) returns 7 ; NOTE using the integer methods on a float will ALWAYS round down.

  • Example: float(7) returns 7.0

  • Example: str(42) returns "The Meaning of Life"; actually, it doesn’t, but that would be cool. this method actually returns "42".

BASIC METHODS

Length - Python’s length method can be used on strings to count the number of characters

  • Example: len("Chris") returns 5

Upper & Lower Case Coercion - The upper and lower methods coerce a string’s value to all upper or lower case, respectively.

  • Example: "Chris".upper() returns "CHRIS"

  • Example: "Chris".lower() returns "chris"

Title - Python’s title method is my favorite method so far because it doesn’t exist in the languages I know. I am used to splicing and slicing arrays at the first index and calling the upper or lower case methods and building a new array. Now that I have seen the title method, I’m almost wholly ‘sold’ on why this is such a popular language.

  • Example: 
    "the lord of the rings: the fellowship of the ring".title()
  • returns 
    "The Lord Of The Rings: The Fellowship Of The Ring"

HOW FREAKING COOL?!

List of all methods - Python’s help methods return a list of available methods for the data type you pass to it.

  • Example: help(str)

COMPARISONS

Python’s comparison logic is similar to Ruby’s and JS’s.

  • A single equals sign “=,” assigns a value to a variable

Example: name = "Chris"

  • A double equals sign “==,” compares the equality between two objects.

Example: "Chris" == "Bob" returns False

  • The Bang operator functions the same

Example: "Chris" != "Bob" returns True

  • The greater-than and less-than logic is also the same.

Example: 4 > 10 returns False

Example: 4 >= 4 returns True

  • String comparison uses alphabetical order, so “b” comes after “a” and therefore is ‘greater’ than “a.”

Example: "banana" > "apple" returns True

BOOLEANS

Python’s conditional logic is the same as in JavaScript and Ruby. The syntax for chaining logical is a little different.

  • Ruby Example: true && true returns true

  • Ruby Example: true || false returns true

  • Python Example: True and True returns True

  • Python Example: True or False returns True

Python’s syntax reads more like English than Ruby’s!

CONDITIONALS

If, Else, and Elif - One of the most significant differences between Ruby and Python is that when we write a conditional statement in Python, the indentation MATTERS.

The ‘if’ statement is followed by the expression we are evaluating, followed by a colon. The block of code we want to run if the condition is met, must be indented or tabbed. If we don’t do that, then that block is not attached to the evaluated expression.

The ‘else’ statement is similar to Ruby and JS as well. If the ‘if’ statement expression is not met, run the ‘else’ statement block.

In Python, the keyword ‘elif’ is a replacement for Ruby’s ‘elsif’ and JS’s ‘else if.’

Example:

if name == "Chris":
    print("Hi, {}! Awesome name!".format(name))
elif name == "Bob":
    print("Howdy, {}! Your name is almost as cool as the name, Chris.".format(name))
else:
    print("Hello, {}. Have you thought about changing your name to Chris?".format(name))

And there you have it! I hope that these blogs are helping turn on some lights and showing you how easy it is to pick up a new language once you have others under your belt. Take another break and get comfortable with these concepts. I think it becomes exponentially more comfortable to learn new things once you have something to compare it to. Next week I’m going to wrap up my Python basics series by covering functions and loops.

Python Basics: Part III