# Python – Flag None Element Rows in Matrix

• Last Updated : 02 Sep, 2020

Given a Matrix, return True for rows which contain a None Value, else return False.

Input : test_list = [[2, 4, None, 3], [3, 4, 1, None], [2, 4, 7, 4], [2, 8, None]]
Output : [True, True, False, True]
Explanation : 1, 2 and 4th index contain None occurrence.

Input : test_list = [[2, 4, None, 3], [3, 4, 1, None], [2, 4, None, 4], [2, 8, None]]
Output : [True, True, True, True]
Explanation : All rows have None.

Method #1 : Using List comprehension

In this, we iterate for each row and use in operator to check for None in these. If found, True is returned, else False is returned.

## Python3

 `# Python3 code to demonstrate working of ``# Flag None Element Rows in Matrix``# Using list comprehension`` ` `# initializing list``test_list ``=` `[[``2``, ``4``, ``None``, ``3``], [``3``, ``4``, ``1``, ``None``], [``2``, ``4``, ``7``, ``4``], [``2``, ``8``]]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# in operator to check None value ``# True if any None is found ``res ``=` `[``True` `if` `None` `in` `sub ``else` `False` `for` `sub ``in` `test_list]`` ` `# printing result ``print``(``"None Flagged List : "` `+` `str``(res))`
Output
```The original list is : [[2, 4, None, 3], [3, 4, 1, None], [2, 4, 7, 4], [2, 8]]
None Flagged List : [True, True, False, False]
```

Method #2 : Using all() + list comprehension

In this, we check for all values to be True using all(), if yes, its not flagged True and list comprehension is used to check for each row.

## Python3

 `# Python3 code to demonstrate working of ``# Flag None Element Rows in Matrix``# Using all() + list comprehension`` ` `# initializing list``test_list ``=` `[[``2``, ``4``, ``None``, ``3``], [``3``, ``4``, ``1``, ``None``], [``2``, ``4``, ``7``, ``4``], [``2``, ``8``]]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# all() checks for all non none values  ``res ``=` `[``False` `if` `all``(sub) ``else` `True` `for` `sub ``in` `test_list]`` ` `# printing result ``print``(``"None Flagged List : "` `+` `str``(res))`
Output
```The original list is : [[2, 4, None, 3], [3, 4, 1, None], [2, 4, 7, 4], [2, 8]]
None Flagged List : [True, True, False, False]
```

My Personal Notes arrow_drop_up