# Python – Extract records if Kth elements not in List

• Difficulty Level : Basic
• Last Updated : 29 Aug, 2020

Given list of tuples, task is to extract all the tuples where Kth index elements are not present in argument list.

Input  :  test_list = [(5, 3), (7, 4), (1, 3), (7, 8), (0, 6)], arg_list = [6, 8, 8], K = 1

Output : [(5, 3), (7, 4), (1, 3)]

Explanation :  All the elements which have either 6 or 8 at 1st index are removed.

Input  :  test_list = [(5, 3), (7, 4)], arg_list = [3, 3, 3, 3], K = 1

Output : [(7, 4)]

Explanation :  (5, 3) is removed as it has 3 at 1st index.

Method #1 : Using set() + loop

This is one way in which this task can be. In this, we shorten the argument list using set and then efficiently check for Kth index having any element from arg. list and append accordingly.

## Python3

 `# Python3 code to demonstrate working of``# Extract records if Kth elements not in List``# Using loop`` ` `# initializing list``test_list ``=` `[(``5``, ``3``), (``7``, ``4``), (``1``, ``3``), (``7``, ``8``), (``0``, ``6``)]`` ` `# printing original list``print``(``"The original list : "` `+` `str``(test_list))`` ` `# initializing arg. list``arg_list ``=` `[``4``, ``8``, ``4``]`` ` `# initializing K``K ``=` `1`` ` `# Using set() to shorten arg list``temp ``=` `set``(arg_list)`` ` `# loop to check for elements and append``res ``=` `[]``for` `sub ``in` `test_list:``    ``if` `sub[K] ``not` `in` `arg_list:``        ``res.append(sub)`` ` `# printing result``print``(``"Extracted elements : "` `+` `str``(res))`

Output

```The original list : [(5, 3), (7, 4), (1, 3), (7, 8), (0, 6)]
Extracted elements : [(5, 3), (1, 3), (0, 6)]

```

Method #2 : Using list comprehension + set()

This is yet another way in which this task can be performed. In this, we compile both, task of filtering duplicates using set() and compiling elements using conditionals inside list comprehension.

## Python3

 `# Python3 code to demonstrate working of``# Extract records if Kth elements not in List``# Using list comprehension + set()`` ` `# initializing list``test_list ``=` `[(``5``, ``3``), (``7``, ``4``), (``1``, ``3``), (``7``, ``8``), (``0``, ``6``)]`` ` `# printing original list``print``(``"The original list : "` `+` `str``(test_list))`` ` `# initializing arg. list``arg_list ``=` `[``4``, ``8``, ``4``]`` ` `# initializing K``K ``=` `1`` ` `# Compiling set() and conditionals into single comprehension``res ``=` `[(key, val) ``for` `key, val ``in` `test_list ``if` `val ``not` `in` `set``(arg_list)]`` ` `# printing result``print``(``"Extracted elements : "` `+` `str``(res))`

Output

```The original list : [(5, 3), (7, 4), (1, 3), (7, 8), (0, 6)]
Extracted elements : [(5, 3), (1, 3), (0, 6)]

```

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