Added doctests to bucket sort (TheAlgorithms#2079)

* Added doctests to bucket sort

* Missing typehint

* Wrap long lines

* updating DIRECTORY.md

* Update bucket_sort.py

* updating DIRECTORY.md

* Update bucket_sort.py

Co-authored-by: Christian Clauss <cclauss@me.com>
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

Author: 3 people

DIRECTORY.md

@@ -147,6 +147,7 @@
     * [Trie](https://github.com/TheAlgorithms/Python/blob/master/data_structures/trie/trie.py)
 
 ## Digital Image Processing
+  * [Change Brightness](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/change_brightness.py)
   * [Change Contrast](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/change_contrast.py)
   * [Convert To Negative](https://github.com/TheAlgorithms/Python/blob/master/digital_image_processing/convert_to_negative.py)
   * Dithering
@@ -268,6 +269,7 @@
 ## Hashes
   * [Adler32](https://github.com/TheAlgorithms/Python/blob/master/hashes/adler32.py)
   * [Chaos Machine](https://github.com/TheAlgorithms/Python/blob/master/hashes/chaos_machine.py)
+  * [Djb2](https://github.com/TheAlgorithms/Python/blob/master/hashes/djb2.py)
   * [Enigma Machine](https://github.com/TheAlgorithms/Python/blob/master/hashes/enigma_machine.py)
   * [Hamming Code](https://github.com/TheAlgorithms/Python/blob/master/hashes/hamming_code.py)
   * [Md5](https://github.com/TheAlgorithms/Python/blob/master/hashes/md5.py)

sorts/bucket_sort.py

@@ -1,34 +1,54 @@
-#!/usr/bin/env python
-
-"""Illustrate how to implement bucket sort algorithm."""
-
-# Author: OMKAR PATHAK
-# This program will illustrate how to implement bucket sort algorithm
-
-# Wikipedia says: Bucket sort, or bin sort, is a sorting algorithm that works
-# by distributing the elements of an array into a number of buckets.
-# Each bucket is then sorted individually, either using a different sorting
-# algorithm, or by recursively applying the bucket sorting algorithm. It is a
-# distribution sort, and is a cousin of radix sort in the most to least
-# significant digit flavour.
-# Bucket sort is a generalization of pigeonhole sort. Bucket sort can be
-# implemented with comparisons and therefore can also be considered a
-# comparison sort algorithm. The computational complexity estimates involve the
-# number of buckets.
-
-#  Time Complexity of Solution:
-#  Worst case scenario occurs when all the elements are placed in a single bucket. The
-# overall performance would then be dominated by the algorithm used to sort each bucket.
-# In this case, O(n log n), because of TimSort
-#
-#  Average Case O(n + (n^2)/k + k), where k is the number of buckets
-#
-#  If k = O(n), time complexity is O(n)
+#!/usr/bin/env python3
+"""
+Illustrate how to implement bucket sort algorithm.
 
+Author: OMKAR PATHAK
+This program will illustrate how to implement bucket sort algorithm
+
+Wikipedia says: Bucket sort, or bin sort, is a sorting algorithm that works
+by distributing the elements of an array into a number of buckets.
+Each bucket is then sorted individually, either using a different sorting
+algorithm, or by recursively applying the bucket sorting algorithm. It is a
+distribution sort, and is a cousin of radix sort in the most to least
+significant digit flavour.
+Bucket sort is a generalization of pigeonhole sort. Bucket sort can be
+implemented with comparisons and therefore can also be considered a
+comparison sort algorithm. The computational complexity estimates involve the
+number of buckets.
+
+Time Complexity of Solution:
+Worst case scenario occurs when all the elements are placed in a single bucket.
+The overall performance would then be dominated by the algorithm used to sort each
+bucket. In this case, O(n log n), because of TimSort
+
+Average Case O(n + (n^2)/k + k), where k is the number of buckets
+
+If k = O(n), time complexity is O(n)
+
+Source: https://en.wikipedia.org/wiki/Bucket_sort
+"""
 DEFAULT_BUCKET_SIZE = 5
 
 
-def bucket_sort(my_list, bucket_size=DEFAULT_BUCKET_SIZE):
+def bucket_sort(my_list: list, bucket_size: int = DEFAULT_BUCKET_SIZE) -> list:
+    """
+    >>> data = [-1, 2, -5, 0]
+    >>> bucket_sort(data) == sorted(data)
+    True
+
+    >>> data = [9, 8, 7, 6, -12]
+    >>> bucket_sort(data) == sorted(data)
+    True
+
+    >>> data = [.4, 1.2, .1, .2, -.9]
+    >>> bucket_sort(data) == sorted(data)
+    True
+
+    >>> bucket_sort([])
+    Traceback (most recent call last):
+      ...
+    Exception: Please add some elements in the array.
+    """
     if len(my_list) == 0:
         raise Exception("Please add some elements in the array.")
 
@@ -40,11 +60,10 @@ def bucket_sort(my_list, bucket_size=DEFAULT_BUCKET_SIZE):
         buckets[int((my_list[i] - min_value) // bucket_size)].append(my_list[i])
 
     return sorted(
-        [buckets[i][j] for i in range(len(buckets)) for j in range(len(buckets[i]))]
+        buckets[i][j] for i in range(len(buckets)) for j in range(len(buckets[i]))
     )
 
 
 if __name__ == "__main__":
-    user_input = input("Enter numbers separated by a comma:").strip()
-    unsorted = [float(n) for n in user_input.split(",") if len(user_input) > 0]
-    print(bucket_sort(unsorted))
+    assert bucket_sort([4, 5, 3, 2, 1]) == [1, 2, 3, 4, 5]
+    assert bucket_sort([0, 1, -10, 15, 2, -2]) == [-10, -2, 0, 1, 2, 15]