# Python | Farthest point on horizontal lines in 2D plane

• Last Updated : 27 Aug, 2019

Sometimes, while in competitive programming, we might be facing a problem which is of geometry domain and works with x-y coordinate system. The list of tuple can be used to store the same. And along with this, there might be a problem in which we need point with max value of x axis with similar y axis i.e farthest point on horizontal lines. Let’s discuss certain ways to discuss this problem.

Method : Using list comprehension + `max()`
This is a generic brute force method applied to get the max x axis point for common y axis, made as 1 liner using list comprehension. The `max()` is used to find the max of x axis element.

 `# Python3 code to demonstrate working of ` `# Farthest point on horizontal lines in 2D plane ` `# Using list comprehension + max() ` `from` `collections ``import` `defaultdict ` ` `  `# initializing list ` `test_list ``=` `[(``1``, ``6``), (``4``, ``6``), (``2``, ``6``), (``6``, ``8``), (``1``, ``8``), (``2``, ``9``)] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+`  `str``(test_list)) ` ` `  `# Using list comprehension + max() ` `# Farthest point on horizontal lines in 2D plane ` `temp ``=` `defaultdict(``list``) ` `for` `key, val ``in` `test_list: ` `   ``temp[val].append(key) ` `res ``=` `[(key, val) ``for` `key, val ``in` `test_list ``if` `max``(temp[val]) ``=``=` `key] ` ` `  `# Printing result ` `print``(``"The list after filtering just maximum points on lines : "` `+`  `str``(res)) `

Output :

```The original list is : [(1, 6), (4, 6), (2, 6), (6, 8), (1, 8), (2, 9)]
The list after filtering just maximum points on lines : [(4, 6), (6, 8), (2, 9)]
```
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