# Python program to Test if all y occur after x in List

• Last Updated : 16 Nov, 2020

Given a List, test if all occurrences of y are after the occurrence of x in the list.

Input : test_list = [4, 5, 6, 2, 4, 5, 2, 9], x, y = 6, 2
Output : True
Explanation : All occurrences of 2 are after 6, hence true.

Input : test_list = [4, 2, 5, 6, 2, 4, 5, 2, 9], x, y = 6, 2
Output : False
Explanation : All occurrences of 2 are not after 6, hence true.

Method #1 : Using loop + index()

In this, we check for an index of x in the list, and then run a loop to get the occurrence of y, if any y occurs before x index, the result is False.

## Python3

 `# Python3 code to demonstrate working of ``# Test if y occurs after x in List``# Using loop + index()`` ` `# initializing list``test_list ``=` `[``4``, ``5``, ``6``, ``2``, ``4``, ``5``, ``2``, ``9``]`` ` `# printing original lists``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing x, y ``x, y ``=` `6``, ``2`` ` `# getting index of x ``xidx ``=` `test_list.index(x)`` ` `res ``=` `True` `for` `idx, ele ``in` `enumerate``(test_list):``     ` `    ``# checking for y and comparing index ``    ``if` `ele ``=``=` `y ``and` `idx < xidx:``        ``res ``=` `False` `        ``break`` ` `# printing result ``print``(``"Do all y occur after x : "` `+` `str``(res))`

Output:

```The original list is : [4, 5, 6, 2, 4, 5, 2, 9]
Do all y occur after x : True```

Method #2 : Using all() + index()

In this, we test for all the indices of y using all(), and index() is used to get the index of x in the list.

## Python3

 `# Python3 code to demonstrate working of ``# Test if y occurs after x in List``# Using all() + index()`` ` `# initializing list``test_list ``=` `[``4``, ``5``, ``6``, ``2``, ``4``, ``5``, ``2``, ``9``]`` ` `# printing original lists``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing x, y ``x, y ``=` `6``, ``2`` ` `# getting index of x ``xidx ``=` `test_list.index(x)`` ` `# checking for all indices of y in list ``res ``=` `all``(idx > xidx ``for` `idx, ele ``in` `enumerate``(test_list) ``if` `ele ``=``=` `y)`` ` `# printing result ``print``(``"Do all y occur after x : "` `+` `str``(res))`

Output:

```The original list is : [4, 5, 6, 2, 4, 5, 2, 9]
Do all y occur after x : True```

My Personal Notes arrow_drop_up