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76 lines
2.4 KiB
Python
76 lines
2.4 KiB
Python
#!/usr/bin/env python3
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"""
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Illustrate how to implement bucket sort algorithm.
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Author: OMKAR PATHAK
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This program will illustrate how to implement bucket sort algorithm
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Wikipedia says: Bucket sort, or bin sort, is a sorting algorithm that works
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by distributing the elements of an array into a number of buckets.
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Each bucket is then sorted individually, either using a different sorting
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algorithm, or by recursively applying the bucket sorting algorithm. It is a
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distribution sort, and is a cousin of radix sort in the most to least
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significant digit flavour.
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Bucket sort is a generalization of pigeonhole sort. Bucket sort can be
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implemented with comparisons and therefore can also be considered a
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comparison sort algorithm. The computational complexity estimates involve the
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number of buckets.
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Time Complexity of Solution:
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Worst case scenario occurs when all the elements are placed in a single bucket.
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The overall performance would then be dominated by the algorithm used to sort each
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bucket. In this case, O(n log n), because of TimSort
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Average Case O(n + (n^2)/k + k), where k is the number of buckets
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If k = O(n), time complexity is O(n)
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Source: https://en.wikipedia.org/wiki/Bucket_sort
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"""
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from __future__ import annotations
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def bucket_sort(my_list: list, bucket_count: int = 10) -> list:
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"""
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>>> data = [-1, 2, -5, 0]
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>>> bucket_sort(data) == sorted(data)
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True
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>>> data = [9, 8, 7, 6, -12]
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>>> bucket_sort(data) == sorted(data)
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True
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>>> data = [.4, 1.2, .1, .2, -.9]
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>>> bucket_sort(data) == sorted(data)
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True
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>>> bucket_sort([]) == sorted([])
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True
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>>> data = [-1e10, 1e10]
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>>> bucket_sort(data) == sorted(data)
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True
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>>> import random
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>>> collection = random.sample(range(-50, 50), 50)
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>>> bucket_sort(collection) == sorted(collection)
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True
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"""
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if len(my_list) == 0 or bucket_count <= 0:
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return []
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min_value, max_value = min(my_list), max(my_list)
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bucket_size = (max_value - min_value) / bucket_count
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buckets: list[list] = [[] for _ in range(bucket_count)]
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for val in my_list:
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index = min(int((val - min_value) / bucket_size), bucket_count - 1)
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buckets[index].append(val)
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return [val for bucket in buckets for val in sorted(bucket)]
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if __name__ == "__main__":
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from doctest import testmod
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testmod()
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assert bucket_sort([4, 5, 3, 2, 1]) == [1, 2, 3, 4, 5]
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assert bucket_sort([0, 1, -10, 15, 2, -2]) == [-10, -2, 0, 1, 2, 15]
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