Merge pull request OmkarPathak#78 from IanDoarn/master

Implemented Radix Sorting, thanks @ashaywalke

Author: Ian Doarn

pygorithm/sorting/__init__.py

@@ -8,6 +8,7 @@
 from . import counting_sort
 from . import insertion_sort
 from . import merge_sort
+from . import radix_sort
 from . import selection_sort
 from . import shell_sort
 
@@ -19,6 +20,7 @@
     'insertion_sort',
     'merge_sort',
     'quick_sort',
+    'radix_sort',
     'selection_sort',
     'shell_sort'
 ]

pygorithm/sorting/radix_sort.py

@@ -0,0 +1,38 @@
+"""
+Author: Ian Doarn
+Date: 31st Oct 2017
+
+Reference:
+ https://stackoverflow.com/questions/35419229/python-radix-sort
+"""
+
+
+def sort(_list, base=10):
+    """
+    Radix Sort
+    
+    :param _list: array to sort
+    :param base: base radix number
+    :return: sorted list
+    """
+    # TODO: comment this
+
+    result_list = []
+    power = 0
+    while _list:
+        bs = [[] for _ in range(base)]
+        for x in _list:
+            bs[x // base ** power % base].append(x)
+        _list = []
+        for b in bs:
+            for x in b:
+                if x < base ** (power + 1):
+                    result_list.append(x)
+                else:
+                    _list.append(x)
+        power += 1
+    return result_list
+
+
+if __name__ == '__main__':
+    print(sort([170, 45, 75, 90, 802, 24, 2, 66]))

tests/test_sorting.py

@@ -10,7 +10,8 @@
     counting_sort,
     bucket_sort,
     shell_sort,
-    heap_sort)
+    heap_sort,
+    radix_sort)
 
 
 class TestSortingAlgorithm(unittest.TestCase):
@@ -105,5 +106,16 @@ def test_heap_sort(self):
         self.alphaResult = heap_sort.sort(self.alphaArray)
         self.assertEqual(self.alphaResult, self.sorted_alpha_array)
 
+
+class TestRadixSort(TestSortingAlgorithm):
+    def test_radix_sort(self):
+        self.result = radix_sort.sort(self.array)
+        self.assertEqual(self.result, self.sorted_array)
+
+        # TODO: Fix radix sort to sort alphabetically
+        # self.alphaResult = radix_sort.sort(self.alphaArray)
+        # self.assertEqual(self.alphaResult, self.sorted_alpha_array)
+
+
 if __name__ == '__main__':
     unittest.main()