Flatten list of list using list comprehension

list_comprehension_flatten_list_of_lists.py

# 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.
# Syntax: 
#   list_object = [expression_on_item_in_inner_iterable
#                  for_item_in_outer_iterable for_item_in_inner_iterable]
flattened_list = [number for each_list in matrix for number in each_list]

print(flattened_list) # Output: [1, 2, 3, 4, 5, 6, 7, 8, 9]