1st session: Fundamentals of coding with Python

Today we learnt about the Fundamentals of coding using Python, we went through the data types, operators, variables, printing and inputs. I have outlined my notes below.

Python

• An interpreted high level and general programming language
• Can be used on a server to create web applications
• Can be used alongside software to create workflows
• Python relies on indentation

IDE (Integrated Development Environment)

• VSCode
• PyCharm
• Google Colab (alternative to Jupyter notebook)

Objects

• Every entity is an object
• Each object is allocated some space in memory and each object has a type (data type) and some value
• You can check the type of an object using object()

Built-in Data types

Text type - String

Numeric type - Integer, Float, Complex

Sequence type - List, Tuple, Range

Mapping type - Dict

Set type - Set, Frozenset

Boolean type - Bool

Binary type - Bytes, ByteArray, Memoryview

• String - “This is a string”
• Integer - 3, 6 (whole numbers)
• Float - 1.332, 5.6 (decimal numbers)
• Boolean - True or False
• Complex number is a number that can be written in the form of (a+b j) where a and b are real numbers, j is an imaginary number.

# Example of a Complex 
The Number is:
(3+2j)

Data type of Number is:
<class 'complex'>

• You can get the data type of any object by using the type() function:

type(10)
<class 'int'>

type(4.2)
<class 'float'>

type(2+3j)
<class 'complex'>

type('I am too.')
<class 'str'>

type(True)
<class 'bool'>

Expressions

• You can combine objects with operators like + and - to form expressions
• A sequence of operands and operators, like a + b - 5 , is called an expression.

Arithmetic operators

• Order of operators follows BIDMAS

Addition - Sum of two a and b

# Operator sign +(binary)
a + b

Subtraction - b subtracted from a

# Operator sign -(binary)
a - b

Multiplication - Product of a and b

# Operator sign *
a * b

Division - Quotient when a is divided by b, the result is always a float.

# Operator sign /
a / b

Modulo - The remainder when a is divided by b

# Operator sign %
a % b

Floor Division - Quotient when a is divided by b, which is rounded down

# Operator sign //
a // b

Exponentiation - a is raised to the power of b

# Operator sign **
a ** b

"python" + 3

TypeError: can only concatenate str (not "int") to str

• You can only add two strings together, you cannot add a string to an integer

Comparison operators

Comparison operators are used to compare values. It returns either True or False according to the condition.

Logical operators

Logical operators are the and, or, not operators.

Variables Naming

• Use PEP8 style guide
• Variable names can contain letters, numbers and underscore
• Variable names cannot contain spaces
• Variable names cannot start with a number
• Python is case sensitive - separated by underscores
• There are a list of reserved words in python that cannot be used as variable names

Variables

• A Variable is a name that refers to an object
• One of the main purposes of a variable is to remember a value from one part of a program so that it can be used in another part of the program
• We can assign an object to a variable with an assignment operator (=)
• Double equals (==) checks for equality

Printing

• The print function requires parenthesis around its arguments

print('3+4') // outputs 3+4
print(3+4) // outputs 7

• To print several things at once, separate them by commas. Python will automatically insert spaces between them.

print('The value of 3+4 is', 3+4) 

// outputs The value of 3+4 is 7

Inputs

• An input function is a simple way for your program to get information from people using your program

name = input("Enter your name: ")

<variable name> = input("Message")

• using fstrings

Literal String Interpolation or more commonly as F-strings

To create an f-string, prefix the string with the letter “ f ”. 
The string itself can be formatted in much the same way that you would with str.format().

# This is a program that asks for user name and prints it using a fstring

name = input("Please enter your name: ")
print(f"Welcome, {name}")

• Input functions (user input) are always stored as a string
• To store it as a integer, wrap it in an integer function

  age = int(input("Enter your age: "))
  print(f"You are {age}, you are too old")