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Python progran to extract rows with common difference elements
• Last Updated : 12 Nov, 2020

Given a Matrix, extract rows with AP sequence.

Input : test_list = [[4, 7, 10], [8, 10, 12], [10, 11, 13], [6, 8, 10]]
Output : [[4, 7, 10], [8, 10, 12], [6, 8, 10]]
Explanation : 3, 4, and 2 are common difference in AP.

Input : test_list = [[4, 7, 10], [8, 10, 13], [10, 11, 13], [6, 8, 10]]
Output : [[4, 7, 10], [6, 8, 10]]
Explanation : 3 and 2 are common difference in AP.

Method #1: Using loop

In this, we check for all the elements having a common difference using a loop, if any element not found to be in sync, then the row is flagged off and not added to the result.

## Python3

 `# Python3 code to demonstrate working of ``# Extract rows with common difference elements``# Using loop`` ` `# initializing list``test_list ``=` `[[``4``, ``7``, ``10``],``             ``[``8``, ``10``, ``12``],``             ``[``10``, ``11``, ``13``], ``             ``[``6``, ``8``, ``10``]]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))``         ` `res ``=` `[]``for` `row ``in` `test_list:``    ``flag ``=` `True` `    ``for` `idx ``in` `range``(``0``, ``len``(row) ``-` `1``):``         ` `        ``# check for common difference``        ``if` `row[idx ``+` `1``] ``-` `row[idx] !``=` `row[``1``] ``-` `row[``0``]:``            ``flag ``=` `False` `            ``break``    ``if` `flag :``        ``res.append(row)`` ` `# printing result ``print``(``"Filtered Matrix : "` `+` `str``(res))`

Output:

The original list is : [[4, 7, 10], [8, 10, 12], [10, 11, 13], [6, 8, 10]]
Filtered Matrix : [[4, 7, 10], [8, 10, 12], [6, 8, 10]]

Method #2: Using all() + list comprehension

In this, we check for all values to have common difference using all(), list comprehension is used to perform an iteration of rows.

## Python3

 `# Python3 code to demonstrate working of ``# all() + list comprehension``# Using list comprehension + all()`` ` `# initializing list``test_list ``=` `[[``4``, ``7``, ``10``],``             ``[``8``, ``10``, ``12``],``             ``[``10``, ``11``, ``13``], ``             ``[``6``, ``8``, ``10``]]`` ` `# printing original list``print``(``"The original list is : "` `+` `str``(test_list))`` ` `# checking for all values to have common difference         ``res ``=` `[row ``for` `row ``in` `test_list``       ``if` `all``(row[idx ``+` `1``] ``-` `row[idx] ``=``=` `row[``1``] ``-` `row[``0``]``              ``for` `idx ``in` `range``(``0``, ``len``(row) ``-` `1``))]`` ` `# printing result ``print``(``"Filtered Matrix : "` `+` `str``(res))`

Output:

The original list is : [[4, 7, 10], [8, 10, 12], [10, 11, 13], [6, 8, 10]]
Filtered Matrix : [[4, 7, 10], [8, 10, 12], [6, 8, 10]]

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