ShyamaSankar

# Create an empty dictionary using {}.
employees = {}
print(employees) # Output: {}
print(type(employees)) # Output: <class 'dict'>

# Create a dictionary with items using {}.
employees = {1: 'Tom', 2: 'Macy', 3: 'Sam'}
print(employees) # Output: {1: 'Tom', 2: 'Macy', 3: 'Sam'}

# Create an empty dictionary using dict() constructor.

ShyamaSankar

# Create an empty set using the constructor method.
numbers = set() 
print(numbers) # Output: set()
# Note: {} creates a dictionary in Python.
print(type({})) # Output: <class 'dict'>

# set() constructor function takes an iterable as input.
numbers = set([1, 2])
print(numbers) # Output: {1, 2}
string_set = set("hello")

ShyamaSankar

#### Tuple creation #####
# Create a tuple, also called tuple packing.
numbers = 1, 2
print(numbers) # Output: (1, 2) <- Note that it is represented with an enclosing paranthesis
# Create tuple with paranthesis.
numbers = (1, 2, 3)
print(numbers) # Output: (1, 2, 3)
# Create an empty tuple.
numbers = ()
print(numbers) # Output: ()

ShyamaSankar

# Create an empty list using square brackets.
numbers = []
print(numbers) # Output: []

# Create an empty list using list().
numbers = list()
print(numbers) # Output: []

# Create a list of numbers.
numbers = [1, 2, 3]

ShyamaSankar

# Our list of lists.
matrix_1 = [[1,1,1], [2,2,2], [3,3,3]]
matrix_2 = [[4,4,4], [5,5,5], [6,6,6]]

# Matrix addition with for loop.
# Assuming that the matrices are of the same dimensions
matrix_sum = []
for row in range(len(matrix_1)):
  matrix_sum.append([])
  for column in range(len(matrix[0])):

ShyamaSankar

# Our list of lists.
matrix = [[1,2,3], [4,5,6], [7,8,9]]

# For loop to flatten the matrix.
flattened_list = []
for each_list in matrix:
  for number in each_list:
      flattened_list.append(number)
  
# Rewrite using list comprehension.

ShyamaSankar

substrings_list = ["an", "the"]
strings_list = ["an apple", "the tree", "all trees", "an apple in the tree"]

# For loop to create a list of (substring, string) tuples from two lists.
# First is a list substrings and the second is a list of strings to be parsed.
tuple_list = []
for string in strings_list:
  for substring in substrings_list:
    if substring in string:
      tuple_list.append((substring, string))

ShyamaSankar

# For loop to create a list with all even multiples of 5 (nothing but multiples of 10 :/).
filtered_list = []
for number in range(1, 101):
  if number % 2 == 0:
    if number % 5 == 0:
      filtered_list.append(number)
  
# Rewrite using list comprehension.
# Syntax: 
#   list_object = [expression_on_item for_item_in_iterable if_condition_1_on_item if_condition_2_on_item]

ShyamaSankar

# Original list of numbers.
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

def modifier(number):
  """
  Returns 0 if number is a multiple of 2, 1 if number is a multiple of 3
  and otherwise, the number itself.
  """
  return 0 if number % 2 == 0 else 1 if number % 3 == 0 else number

ShyamaSankar

# Original list of numbers.
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

# For loop to create a new list where we substitute all multiples of 2 by 0,
# multiples of 3(which are not multiples of 2) by 1 and leave the rest as it is.
modified_numbers = []
for number in numbers:
  if number % 2 == 0:
    modified_numbers.append(0)
  elif number % 3 == 0: