When it is required to sort rows of a matrix by custom element count, a method is defined that uses the list comprehension and ‘len’ method to find the output.
Below is a demonstration of the same −
Example
def get_count_matrix(my_key):
return len([element for element in my_key if element in custom_list])
my_list = [[31, 5, 22, 7], [85, 5], [9, 11, 22], [7, 48]]
print("The list is :")
print(my_list)
custom_list = [31, 85, 7]
my_list.sort(key=get_count_matrix)
print("The resultant list is :")
print(my_list)Output
The list is : [[31, 5, 22, 7], [85, 5], [9, 11, 22], [7, 48]] The resultant list is : [[9, 11, 22], [85, 5], [7, 48], [31, 5, 22, 7]]
Explanation
A method named ‘get_count_matrix’ is defined that takes a key as a parameter.
It uses list comprehension to iterate over the list and checks if the specific key is present in the element.
If yes, its length is returned using the ‘len’ method.
Outside the method, a list of list is defined and is displayed on the console.
Another list with integers is defined.
The list is sorted using the ‘sort’ method, and specifying the key as the previously defined method.
This list is displayed as output on the console.