Python supports a list as its list element and hence a matrix can be formed. Sometimes we might have a utility in which we require to perform None check in that list of list i.e matrix and its a very common in all the domains of coding, especially Data Science. Let’s discuss certain ways in which this can be performed.
Method #1: Using any() + list comprehension The any function can be used to perform the task of if condition and the check for each element in the nested list can be computed using the list comprehension.
Python3
# Python3 code to demonstrate# Search in Matrix# using any() + list comprehension# initializing listtest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))# using any() + list comprehension# to Search in Matrixres = any(None in sub for sub in test_list)# printing resultprint("Does Matrix contain None value ? : " + str(res)) |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Time Complexity: O(n*m) where n is the number of rows in the matrix and m is the number of columns in the matrix
Auxiliary Space: O(1)
Method #2 : Using set.issubset() + itertools.chain() The issubset method can be used to check for the membership in sublist and chain function can be used to perform this task for the each element in the Matrix, in a faster way as it works on iterators.
Python3
# Python3 code to demonstrate# Check for None value in Matrix# using set.issubset() + itertools.chain()from itertools import chain# initializing listtest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))# using set.issubset() + itertools.chain()# to Search in Matrixres = {None}.issubset(chain.from_iterable(test_list))# printing resultprint("Does Matrix contain None value ? : " + str(res)) |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Time Complexity: O(n*m) where n is the number of rows in the matrix and m is the number of columns in the matrix
Auxiliary Space: O(1)
Method #3 : Using extend() method and in operator
Python3
# Python3 code to demonstrate# Search None in Matrix# initializing listtest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))res=Falsex=[]for i in test_list: x.extend(i)if None in x: res=True# printing resultprint("Does Matrix contain None value ? : " + str(res)) |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Time Complexity: O(n)
Auxiliary Space: O(n)
Method #4 : Using filter()+lambda functions
Python3
# Python3 code to demonstrate# Search in Matrix# initializing listtest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))res = []for i in test_list: res.extend(i)res = list(filter(lambda x: x == None, res))if(res): res = Trueelse: res = False# printing resultprint("Does Matrix contain None value ? : " + str(res)) |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Time Complexity: O(N*N)
Auxiliary Space: O(N*N)
Method #5 : Using extend() and count() methods
Python3
# Python3 code to demonstrate# Search None in Matrix# initializing listtest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))res=Falsex=[]for i in test_list: x.extend(i)if x.count(None)>=1: res=True# printing resultprint("Does Matrix contain None value ? : " + str(res)) |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Time Complexity : O(N)
Auxiliary Space : O(N)
Method#6: Using itertools.chain() and any()
Python3
import itertoolstest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))res = any(val == None for val in itertools.chain(*test_list))print("Does Matrix contain None value ? : " + str(res))#This code is contributed by Vinay Pinjala. |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Method#7: Convert to string and check for None
Time Complexity : O(N)
Auxiliary Space : O(1)
Python3
# Python3 code to demonstrate# Search None in Matrix# initializing listtest_list = [[4, 5, 6], [10, 2, None], [1, 11, 18]]# printing original listprint("The original list : " + str(test_list))res = "None" in str(test_list)# printing resultprint("Does Matrix contain None value ? : " + str(res))#This code is contributed by Edula Vinay Kumar Reddy |
The original list : [[4, 5, 6], [10, 2, None], [1, 11, 18]] Does Matrix contain None value ? : True
Time Complexity : O(N)
Auxiliary Space : O(1)
