When it is required to remove the first diagonal elements from a square matrix, the ‘enumerate’ and list comprehension is used.
Example
Below is a demonstration of the same
my_list = [[45, 67, 85, 42, 11], [78, 99, 10, 13, 0], [91, 23, 23, 64, 23], [91, 11, 22, 14, 35]]
print("The list is :")
print(my_list)
my_result = []
for index, element in enumerate(my_list):
my_result.append([ele for index_1, ele in enumerate(element) if index_1 != index])
print("The resultant matrix is :")
print(my_result)Output
The list is : [[45, 67, 85, 42, 11], [78, 99, 10, 13, 0], [91, 23, 23, 64, 23], [91, 11, 22, 14, 35]] The resultant matrix is : [[67, 85, 42, 11], [78, 10, 13, 0], [91, 23, 64, 23], [91, 11, 22, 35]]
Explanation
A list of list is defined and is displayed on the console.
An empty list is defined.
The list is iterated over using ‘enumerate’.
The list comprehension is used within the iteration previously.
Here, it is checked to see if the element’s index is same as index of enumerated element.
If they are not equal, it is appended to the empty list.
This is displayed as the output on the console.