Python – List Elements Grouping in Matrix

When it is required to list elements grouping in a matrix, a simple iteration, the ‘pop’ method, list comprehension and ‘append’ methods are used.

Example

Below is a demonstration of the same −

my_list = [[14, 62], [51, 23], [12, 62], [78, 87], [41, 14]]

print("The list is :")
print(my_list)

check_list = [14, 12, 41, 62]
print("The list is :")
print(check_list)

my_result = []
while my_list:

   sub_list_1 = my_list.pop()

   sub_list_2 = [element for element in check_list if element not in sub_list_1]
   try:

      my_list.remove(sub_list_2)

      my_result.append([sub_list_1, sub_list_2])
   except ValueError:

      my_result.append(sub_list_1)

print("The result is :")
print(my_result)

Output

The list is :
[[14, 62], [51, 23], [12, 62], [78, 87], [41, 14]]
The list is :
[14, 12, 41, 62]
The result is :
[[[41, 14], [12, 62]], [78, 87], [51, 23], [14, 62]]

Explanation

• A list of list of integers is defined and is displayed on the console.

• Another list of integers is defined and displayed on the console.

• An empty list is defined.

• A simple iteration is used, and the top most element is popped using ‘pop’ method.

• This is assigned to a variable ‘sub_list_1’.

• A list comprehension is used to iterate over the second list, and check if element is not there in ‘sub_list_1’.

• The ‘try’ and ‘except’ block is used to append specific elements to the empty list.

• This list is displayed as the output on the console.