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# Python program to mask a list using values from another list

• Last Updated : 05 Apr, 2021

Given two lists, the task is to write a python program that marks 1 for elements present in the other list else mark 0.

Input : test_list = [5, 2, 1, 9, 8, 0, 4], search_list = [1, 10, 8, 3, 9]

Output : [0, 0, 1, 1, 1, 0, 0]

Explanation : 1, 9, 8 are present in test_list at position 2, 3, 4 and are masked by 1. Rest are masked by 0.

Input : test_list = [5, 2, 1, 19, 8, 0, 4], search_list = [1, 10, 8, 3, 9]

Output : [0, 0, 1, 0, 1, 0, 0]

Explanation : 1, 8 are present in test_list at position 2, 4 and are masked by 1. Rest are masked by 0.

Method #1: Using list comprehension

In this, we iterate through search list and in operator used to check composition using list comprehension and assign 1 for presence and 0 for absence.

## Python3

 `# Python3 code to demonstrate working of``# Boolean composition mask in list``# Using list comprehension`` ` `# initializing list``test_list ``=` `[``5``, ``2``, ``1``, ``9``, ``8``, ``0``, ``4``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing search list``search_list ``=` `[``1``, ``10``, ``8``, ``3``, ``9``]`` ` `# list comprehension iteration and in operator``# checking composition``res ``=` `[``1` `if` `ele ``in` `search_list ``else` `0` `for` `ele ``in` `test_list]`` ` `# printing result``print``(``"The Boolean Masked list : "` `+` `str``(res))`

Output:

```The original list is : [5, 2, 1, 9, 8, 0, 4]
The Boolean Masked list : [0, 0, 1, 1, 1, 0, 0]```

Method #2: Using set() + list comprehension

In this, duplicate elements are removed from the search list to reduce search space using set(). Rest all the operations are similar to the above method.

## Python3

 `# Python3 code to demonstrate working of``# Boolean composition mask in list``# Using set() + list comprehension`` ` `# initializing list``test_list ``=` `[``5``, ``2``, ``1``, ``9``, ``8``, ``0``, ``4``]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing search list``search_list ``=` `[``1``, ``10``, ``8``, ``3``, ``9``]`` ` `# list comprehension iteration and in operator``# checking composition``# set() removes duplicates``res ``=` `[``1` `if` `ele ``in` `set``(search_list) ``else` `0` `for` `ele ``in` `test_list]`` ` `# printing result``print``(``"The Boolean Masked list : "` `+` `str``(res))`

Output:

```The original list is : [5, 2, 1, 9, 8, 0, 4]
The Boolean Masked list : [0, 0, 1, 1, 1, 0, 0]```

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