Adding unit tests for sorting functions, and improving readability on some sorting algorithms (#784)

* Adding variable to fade out ambiguity

* More readability on merge sorting algorithm

* Updating merge_sort_fastest description and explaining why

* Adding tests file with imports

* Standardazing filenames and function names

* Adding test cases and test functions

* Adding test loop

* Putting 'user oriented code' inside main condition for having valid imports

* Fixing condition

* Updating tests: adding cases and todo list

* Refactoring first euler problem's first solution

project_euler/problem_01/sol1.py

@@ -10,8 +10,4 @@ try:
 except NameError:
     raw_input = input  # Python 3
 n = int(raw_input().strip())
-sum=0
-for a in range(3,n):
-    if(a%3==0 or a%5==0):
-        sum+=a
-print(sum)
+print(sum([e for e in range(3, n) if e % 3 == 0 or e % 5 == 0]))

sorts/bogo_sort.py

@@ -1,28 +1,28 @@
 """
 This is a pure python implementation of the bogosort algorithm
 For doctests run following command:
-python -m doctest -v bogosort.py
+python -m doctest -v bogo_sort.py
 or
-python3 -m doctest -v bogosort.py
+python3 -m doctest -v bogo_sort.py
 For manual testing run:
-python bogosort.py
+python bogo_sort.py
 """
 
 from __future__ import print_function
 import random
 
 
-def bogosort(collection):
+def bogo_sort(collection):
     """Pure implementation of the bogosort algorithm in Python
     :param collection: some mutable ordered collection with heterogeneous
     comparable items inside
     :return: the same collection ordered by ascending
     Examples:
-    >>> bogosort([0, 5, 3, 2, 2])
+    >>> bogo_sort([0, 5, 3, 2, 2])
     [0, 2, 2, 3, 5]
-    >>> bogosort([])
+    >>> bogo_sort([])
     []
-    >>> bogosort([-2, -5, -45])
+    >>> bogo_sort([-2, -5, -45])
     [-45, -5, -2]
     """
 
@@ -46,4 +46,4 @@ if __name__ == '__main__':
 
     user_input = raw_input('Enter numbers separated by a comma:\n').strip()
     unsorted = [int(item) for item in user_input.split(',')]
-    print(bogosort(unsorted))
+    print(bogo_sort(unsorted))

sorts/cycle_sort.py

@@ -50,11 +50,11 @@ if __name__ == '__main__':
     except NameError:
         raw_input = input  # Python 3
         
-user_input = raw_input('Enter numbers separated by a comma:\n')
-unsorted = [int(item) for item in user_input.split(',')]
-n = len(unsorted)
-cycle_sort(unsorted)
+    user_input = raw_input('Enter numbers separated by a comma:\n')
+    unsorted = [int(item) for item in user_input.split(',')]
+    n = len(unsorted)
+    cycle_sort(unsorted)
 
-print("After sort : ")
-for i in range(0, n):
-    print(unsorted[i], end=' ')
+    print("After sort : ")
+    for i in range(0, n):
+        print(unsorted[i], end=' ')

sorts/insertion_sort.py

@@ -29,10 +29,12 @@ def insertion_sort(collection):
     >>> insertion_sort([-2, -5, -45])
     [-45, -5, -2]
     """
-    for index in range(1, len(collection)):
-        while index > 0 and collection[index - 1] > collection[index]:
-            collection[index], collection[index - 1] = collection[index - 1], collection[index]
-            index -= 1
+
+    for loop_index in range(1, len(collection)):
+        insertion_index = loop_index
+        while insertion_index > 0 and collection[insertion_index - 1] > collection[insertion_index]:
+            collection[insertion_index], collection[insertion_index - 1] = collection[insertion_index - 1], collection[insertion_index]
+            insertion_index -= 1
 
     return collection
 

sorts/merge_sort_fastest.py

@@ -2,7 +2,7 @@
 Python implementation of the fastest merge sort algorithm.
 Takes an average of 0.6 microseconds to sort a list of length 1000 items.
 Best Case Scenario : O(n)
-Worst Case Scenario : O(n)
+Worst Case Scenario : O(n^2) because native python functions:min, max and remove are already O(n)
 '''
 from __future__ import print_function
 

sorts/pancake_sort.py

@@ -1,7 +1,7 @@
 # Pancake sort algorithm 
 # Only can reverse array from 0 to i
 
-def pancakesort(arr):
+def pancake_sort(arr):
     cur = len(arr)
     while cur > 1:
         # Find the maximum number in arr
@@ -13,4 +13,5 @@ def pancakesort(arr):
         cur -= 1
     return arr
 
-print(pancakesort([0,10,15,3,2,9,14,13]))
+if __name__ == '__main__':
+    print(pancake_sort([0,10,15,3,2,9,14,13]))

sorts/radix_sort.py

@@ -1,4 +1,4 @@
-def radixsort(lst):
+def radix_sort(lst):
     RADIX = 10
     placement = 1
 

sorts/tests.py

@@ -0,0 +1,74 @@
+from bogo_sort import bogo_sort
+from bubble_sort import bubble_sort
+from bucket_sort import bucket_sort
+from cocktail_shaker_sort import cocktail_shaker_sort
+from comb_sort import comb_sort
+from counting_sort import counting_sort
+from cycle_sort import cycle_sort
+from gnome_sort import gnome_sort
+from heap_sort import heap_sort
+from insertion_sort import insertion_sort
+from merge_sort_fastest import merge_sort as merge_sort_fastest
+from merge_sort import merge_sort
+from pancake_sort import pancake_sort
+from quick_sort_3_partition import quick_sort_3partition
+from quick_sort import quick_sort
+from radix_sort import radix_sort
+from random_pivot_quick_sort import quick_sort_random
+from selection_sort import selection_sort
+from shell_sort import shell_sort
+from tim_sort import tim_sort
+from topological_sort import topological_sort
+from tree_sort import tree_sort
+from wiggle_sort import wiggle_sort
+
+
+TEST_CASES = [
+    {'input': [8, 7, 6, 5, 4, 3, -2, -5], 'expected': [-5, -2, 3, 4, 5, 6, 7, 8]},
+    {'input': [-5, -2, 3, 4, 5, 6, 7, 8], 'expected': [-5, -2, 3, 4, 5, 6, 7, 8]},
+    {'input': [5, 6, 1, 4, 0, 1, -2, -5, 3, 7], 'expected': [-5, -2, 0, 1, 1, 3, 4, 5, 6, 7]},
+    {'input': [2, -2], 'expected': [-2, 2]},
+    {'input': [1], 'expected': [1]},
+    {'input': [], 'expected': []},
+]
+
+'''
+    TODO:
+    - Fix some broken tests in particular cases (as [] for example),
+    - Unify the input format: should always be function(input_collection) (no additional args)
+    - Unify the output format: should always be a collection instead of updating input elements
+      and returning None
+    - Rewrite some algorithms in function format (in case there is no function definition)
+'''
+
+TEST_FUNCTIONS = [
+    bogo_sort,
+    bubble_sort,
+    bucket_sort,
+    cocktail_shaker_sort,
+    comb_sort,
+    counting_sort,
+    cycle_sort,
+    gnome_sort,
+    heap_sort,
+    insertion_sort,
+    merge_sort_fastest,
+    merge_sort,
+    pancake_sort,
+    quick_sort_3partition,
+    quick_sort,
+    radix_sort,
+    quick_sort_random,
+    selection_sort,
+    shell_sort,
+    tim_sort,
+    topological_sort,
+    tree_sort,
+    wiggle_sort,
+]
+
+
+for function in TEST_FUNCTIONS:
+    for case in TEST_CASES:
+        result = function(case['input'])
+        assert result  == case['expected'], 'Executed function: {}, {} != {}'.format(function.__name__, result, case['expected'])

sorts/tim_sort.py

@@ -41,7 +41,7 @@ def merge(left, right):
     return [right[0]] + merge(left, right[1:])
 
 
-def timsort(lst):
+def tim_sort(lst):
     runs, sorted_runs = [], []
     length = len(lst)
     new_run = [lst[0]]
@@ -75,7 +75,7 @@ def timsort(lst):
 def main():
 
     lst = [5,9,10,3,-4,5,178,92,46,-18,0,7]
-    sorted_lst = timsort(lst)
+    sorted_lst = tim_sort(lst)
     print(sorted_lst)
 
 if __name__ == '__main__':

sorts/topological_sort.py

@@ -28,6 +28,6 @@ def topological_sort(start, visited, sort):
     # return sort
     return sort
 
-
-sort = topological_sort('a', [], [])
-print(sort)
+if __name__ == '__main__':
+    sort = topological_sort('a', [], [])
+    print(sort)

sorts/tree_sort.py

@@ -30,7 +30,7 @@ def inorder(root, res):
         res.append(root.val)
         inorder(root.right,res)
 
-def treesort(arr):
+def tree_sort(arr):
     # Build BST
     if len(arr) == 0:
         return arr
@@ -42,4 +42,5 @@ def treesort(arr):
     inorder(root,res)
     return res
 
-print(treesort([10,1,3,2,9,14,13]))
+if __name__ == '__main__':
+    print(tree_sort([10,1,3,2,9,14,13]))

sorts/wiggle_sort.py

@@ -9,13 +9,11 @@ def wiggle_sort(nums):
         if (i % 2 == 1) == (nums[i-1] > nums[i]):
             nums[i-1], nums[i] = nums[i], nums[i-1]
 
-
-print("Enter the array elements:\n")
-array=list(map(int,input().split()))
-print("The unsorted array is:\n")
-print(array)
-wiggle_sort(array)
-print("Array after Wiggle sort:\n")
-print(array)
-
-
+if __name__ == '__main__':
+    print("Enter the array elements:\n")
+    array=list(map(int,input().split()))
+    print("The unsorted array is:\n")
+    print(array)
+    wiggle_sort(array)
+    print("Array after Wiggle sort:\n")
+    print(array)