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Add doctests to interpolation_search.py (#11492)
* Add doctests to interpolation_search.py * update docs * update tests * update tests 2 * clean code
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@ -3,13 +3,41 @@ This is pure Python implementation of interpolation search algorithm
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"""
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def interpolation_search(sorted_collection, item):
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"""Pure implementation of interpolation search algorithm in Python
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Be careful collection must be ascending sorted, otherwise result will be
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unpredictable
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:param sorted_collection: some ascending sorted collection with comparable items
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:param item: item value to search
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:return: index of found item or None if item is not found
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def interpolation_search(sorted_collection: list[int], item: int) -> int | None:
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"""
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Searches for an item in a sorted collection by interpolation search algorithm.
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Args:
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sorted_collection: sorted list of integers
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item: item value to search
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Returns:
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int: The index of the found item, or None if the item is not found.
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Examples:
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>>> interpolation_search([1, 2, 3, 4, 5], 2)
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1
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>>> interpolation_search([1, 2, 3, 4, 5], 4)
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3
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>>> interpolation_search([1, 2, 3, 4, 5], 6) is None
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True
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>>> interpolation_search([], 1) is None
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True
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>>> interpolation_search([100], 100)
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0
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>>> interpolation_search([1, 2, 3, 4, 5], 0) is None
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True
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>>> interpolation_search([1, 2, 3, 4, 5], 7) is None
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True
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>>> interpolation_search([1, 2, 3, 4, 5], 2)
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1
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>>> interpolation_search([1, 2, 3, 4, 5], 0) is None
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True
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>>> interpolation_search([1, 2, 3, 4, 5], 7) is None
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True
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>>> interpolation_search([1, 2, 3, 4, 5], 2)
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1
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>>> interpolation_search([5, 5, 5, 5, 5], 3) is None
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True
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"""
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left = 0
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right = len(sorted_collection) - 1
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@ -19,8 +47,7 @@ def interpolation_search(sorted_collection, item):
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if sorted_collection[left] == sorted_collection[right]:
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if sorted_collection[left] == item:
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return left
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else:
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return None
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return None
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point = left + ((item - sorted_collection[left]) * (right - left)) // (
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sorted_collection[right] - sorted_collection[left]
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@ -33,7 +60,7 @@ def interpolation_search(sorted_collection, item):
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current_item = sorted_collection[point]
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if current_item == item:
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return point
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elif point < left:
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if point < left:
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right = left
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left = point
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elif point > right:
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@ -46,22 +73,42 @@ def interpolation_search(sorted_collection, item):
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return None
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def interpolation_search_by_recursion(sorted_collection, item, left, right):
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def interpolation_search_by_recursion(
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sorted_collection: list[int], item: int, left: int = 0, right: int | None = None
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) -> int | None:
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"""Pure implementation of interpolation search algorithm in Python by recursion
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Be careful collection must be ascending sorted, otherwise result will be
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unpredictable
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First recursion should be started with left=0 and right=(len(sorted_collection)-1)
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:param sorted_collection: some ascending sorted collection with comparable items
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:param item: item value to search
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:return: index of found item or None if item is not found
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"""
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Args:
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sorted_collection: some sorted collection with comparable items
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item: item value to search
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left: left index in collection
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right: right index in collection
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Returns:
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index of item in collection or None if item is not present
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Examples:
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>>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 0)
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0
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>>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 15)
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4
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>>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 5)
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1
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>>> interpolation_search_by_recursion([0, 5, 7, 10, 15], 100) is None
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True
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>>> interpolation_search_by_recursion([5, 5, 5, 5, 5], 3) is None
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True
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"""
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if right is None:
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right = len(sorted_collection) - 1
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# avoid divided by 0 during interpolation
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if sorted_collection[left] == sorted_collection[right]:
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if sorted_collection[left] == item:
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return left
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else:
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return None
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return None
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point = left + ((item - sorted_collection[left]) * (right - left)) // (
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sorted_collection[right] - sorted_collection[left]
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@ -73,64 +120,18 @@ def interpolation_search_by_recursion(sorted_collection, item, left, right):
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if sorted_collection[point] == item:
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return point
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elif point < left:
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if point < left:
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return interpolation_search_by_recursion(sorted_collection, item, point, left)
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elif point > right:
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if point > right:
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return interpolation_search_by_recursion(sorted_collection, item, right, left)
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elif sorted_collection[point] > item:
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if sorted_collection[point] > item:
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return interpolation_search_by_recursion(
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sorted_collection, item, left, point - 1
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)
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else:
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return interpolation_search_by_recursion(
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sorted_collection, item, point + 1, right
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)
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def __assert_sorted(collection):
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"""Check if collection is ascending sorted, if not - raises :py:class:`ValueError`
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:param collection: collection
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:return: True if collection is ascending sorted
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:raise: :py:class:`ValueError` if collection is not ascending sorted
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Examples:
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>>> __assert_sorted([0, 1, 2, 4])
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True
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>>> __assert_sorted([10, -1, 5])
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Traceback (most recent call last):
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...
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ValueError: Collection must be ascending sorted
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"""
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if collection != sorted(collection):
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raise ValueError("Collection must be ascending sorted")
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return True
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return interpolation_search_by_recursion(sorted_collection, item, point + 1, right)
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if __name__ == "__main__":
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import sys
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import doctest
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"""
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user_input = input('Enter numbers separated by comma:\n').strip()
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collection = [int(item) for item in user_input.split(',')]
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try:
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__assert_sorted(collection)
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except ValueError:
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sys.exit('Sequence must be ascending sorted to apply interpolation search')
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target_input = input('Enter a single number to be found in the list:\n')
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target = int(target_input)
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"""
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debug = 0
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if debug == 1:
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collection = [10, 30, 40, 45, 50, 66, 77, 93]
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try:
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__assert_sorted(collection)
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except ValueError:
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sys.exit("Sequence must be ascending sorted to apply interpolation search")
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target = 67
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result = interpolation_search(collection, target)
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if result is not None:
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print(f"{target} found at positions: {result}")
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else:
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print("Not found")
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doctest.testmod()
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