Converted BinaryHeap to be a ABCMeta class

- Removed tests for BinaryHeap
- Fixed other minor things around

ands/ds/Heap.py

@@ -8,7 +8,7 @@
 
 Created: 01/07/2015
 
-Updated: 13/02/2017
+Updated: 14/02/2017
 
 # Description
 
@@ -22,10 +22,13 @@
 - Chapter 13 of [Introduction to Algorithms (3rd ed.)](https://mitpress.mit.edu/books/introduction-algorithms) by CLRS
 - [NotImplementedError](https://docs.python.org/3/library/exceptions.html#NotImplementedError)
 - [How do I check if an object is an instance of a given class or of a subclass of it?](http://effbot.org/pyfaq/how-do-i-check-if-an-object-is-an-instance-of-a-given-class-or-of-a-subclass-of-it.htm)
+- [https://en.wikipedia.org/wiki/Heap_(data_structure)](https://en.wikipedia.org/wiki/Heap_(data_structure))
+
 """
 
 import io
 import math
+from abc import ABCMeta, abstractmethod
 
 __all__ = ["BinaryHeap", "HeapNode", "build_pretty_binary_heap"]
 
@@ -67,7 +70,7 @@ def __repr__(self):
         return str(self.value) + " -> " + str(self.key)
 
 
-class BinaryHeap:
+class BinaryHeap(metaclass=ABCMeta):
     """Abstract class to represent binary heaps.
 
     `MinHeap`, `MaxHeap` and `MinMaxHeap` all derive from this class."""
@@ -78,27 +81,32 @@ def __init__(self, ls=None):
         self.heap = BinaryHeap._create_list_of_heap_nodes(ls)
         self.build_heap()
 
+    @abstractmethod
     def push_down(self, i: int) -> None:
-        """Classical so-called heapify operation for heaps."""
-        raise NotImplementedError()
+        """Classical _heapify_ operation for heaps."""
+        pass
 
+    @abstractmethod
     def push_up(self, i: int) -> None:
         """Classical reverse-heapify operation for heaps."""
-        raise NotImplementedError()
+        pass
 
+    @abstractmethod
     def delete(self, i: int) -> HeapNode:
-        raise NotImplementedError()
+        """Deletes from self element at index `i` and returns it."""
+        pass
 
+    @abstractmethod
     def replace(self, i: int, x) -> HeapNode:
         """Replaces the `HeapNode` object at index `i` with `x`.
 
         `x` can either be a key or a `HeapNode` object.
         If it's a key, an `HeapNode` is first created,
         whose key and value are equal to `x`."""
-        raise NotImplementedError()
+        pass
 
     def build_heap(self) -> list:
-        """Builds the heap data structure from `self.heap`."""
+        """Builds the heap data structure."""
         if self.heap:
             for index in range(len(self.heap) // 2, -1, -1):
                 self.push_down(index)
@@ -211,8 +219,6 @@ def swap(self, i: int, j: int) -> None:
         else:
             raise IndexError("i or j are not valid indexes.")
 
-    # INDEX FUNCTIONS
-
     def is_good_index(self, i: int) -> bool:
         """Returns `True` if `i` is valid index for `self.heap`,
         `False` otherwise.
@@ -382,12 +388,11 @@ def build_pretty_binary_heap(heap: list, total_width=36, fill=" ") -> str:
 
     output = io.StringIO()
     last_row = -1
-
     h_space = 3.0  # float
     v_space = 2  # int
 
     for i, heap_node in enumerate(heap):
-        if i:
+        if i != 0:
             row = int(math.floor(math.log(i + 1, 2)))
         else:
             row = 0
@@ -396,13 +401,11 @@ def build_pretty_binary_heap(heap: list, total_width=36, fill=" ") -> str:
             output.write("\n" * v_space)
 
         columns = 2 ** row
-
         column_width = int(math.floor((total_width * h_space) / columns))
         output.write(str(heap_node).center(column_width, fill))
         last_row = row
 
     s = output.getvalue() + "\n"
-
     line_length = total_width + 15  # int
     s += ('-' * line_length + "\n")
     return s

ands/ds/MaxHeap.py

@@ -8,7 +8,7 @@
 
 Created: 15/02/2016
 
-Updated: 05/02/2017
+Updated: 14/02/2017
 
 # Description
 
@@ -140,7 +140,7 @@ def replace(self, i: int, x) -> HeapNode:
         return c
 
 
-def is_max_heap(h) -> bool:
+def is_max_heap(h: MaxHeap) -> bool:
     """Returns `True` if `h` is a valid `MaxHeap`. `False` otherwise."""
     if not isinstance(h, MaxHeap):
         return False

ands/ds/MinHeap.py

@@ -8,7 +8,7 @@
 
 Created: 01/07/2015
 
-Updated: 05/02/2017
+Updated: 14/02/2017
 
 # Description
 
@@ -161,7 +161,7 @@ def replace(self, i: int, x) -> HeapNode:
         return c
 
 
-def is_min_heap(h) -> bool:
+def is_min_heap(h: MinHeap) -> bool:
     """Returns `True` if `h` is a valid `MinHeap`. `False` otherwise."""
     if not isinstance(h, MinHeap):
         return False

ands/ds/MinMaxHeap.py

@@ -8,7 +8,7 @@
 
 Created: 18/02/2016
 
-Updated: 29/12/2016
+Updated: 14/02/2017
 
 # Description
 
@@ -25,7 +25,22 @@
 Even levels are 0, 2, 4, 6, etc,
 whereas odd levels are 1, 3, 5, 7, etc.
 
-The most important methods used to build and support the data structure are:
+The public API of this class consists in the following methods:
+
+- add in O(log n) time
+- delete-at in O(log n) time
+- replace-at in O(log n) time
+- remove-min in O(log n) time
+- remove-max in O(log n) time
+- find-min in O(1) time
+- find-max in O(1) time
+- size in O(1) time
+- is-empty in O(1) time
+- contains in O(n) time
+- merge in O(n + m) time
+- clear in O(1) time
+
+And the following are the methods used to build and support the data structure (i.e. the previous operations):
 
 - trickle-down (or, also called, bubble-down or shift-down)
 - trickle-down-min, which is a helper method of trickle-down
@@ -42,23 +57,11 @@
 - find-max-element-index
 - swap
 
-- `add` in O(log n) time
-- `delete-at` in O(log n) time
-- `replace-at` in O(log n) time
-- `remove-min` in O(log n) time
-- `remove-max` in O(log n) time
-- `find-min` in O(1) time
-- `find-max` in O(1) time
-- `size` in O(1) time
-- `is-empty` in O(1) time
-- `contains` in O(n) time
-- `merge` in O(n + m) time
-- `clear` in O(1) time
 
 # TODO
 
-- `find-kth`, i.e. find the kth smallest element in the structure, in O(1) time 
-- `delete-kth`, i.e. delete the kth smallest element, in O(log n) time 
+- find-kth, i.e. find the kth smallest element in the structure, in O(1) time
+- delete-kth, i.e. delete the kth smallest element, in O(log n) time
 
 # References
 
@@ -310,7 +313,7 @@ def index_of_max(self, i: int) -> int:
         return m
 
 
-def is_min_max_heap(h) -> bool:
+def is_min_max_heap(h: MinMaxHeap) -> bool:
     """Returns `True` if `h` is a valid `MinMaxHeap` object. `False` otherwise.
 
     Min-max heap property:

tests/ds/test_BST.py

@@ -5,7 +5,9 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 13/02/2016
+
 Updated: 30/08/2016
 
 # Description

tests/ds/test_BSTNode.py

@@ -5,7 +5,9 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 15/02/2016
+
 Updated: 30/08/2016
 
 # Description

tests/ds/test_DSForests.py

@@ -5,7 +5,9 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 22/02/16
+
 Updated: 03/01/17
 
 # Description

tests/ds/test_HeapNode.py

@@ -6,7 +6,9 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 05/02/2017
+
 Updated: 05/02/2017
 
 # Description

tests/ds/test_LinearProbingHashTable.py

@@ -232,13 +232,13 @@ def test_show(self):
         t = LinearProbingHashTable()
         ls = sample(range(3), 3)
         for elem in ls:
-            t.put(elem, choice(list(string.ascii_letters)))
+            t.put(elem, choice(string.ascii_letters))
         print()
         t.show()
 
     def test_repr(self):
         t = LinearProbingHashTable()
         ls = sample(range(5), 5)
         for elem in ls:
-            t.put(elem, choice(list(string.ascii_letters)))
+            t.put(elem, choice(string.ascii_letters))
         print(repr(t))

tests/ds/test_MaxHeap.py

@@ -5,8 +5,10 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 17/02/2016
-Updated: 05/02/2017
+
+Updated: 14/02/2017
 
 # Description
 
@@ -524,3 +526,11 @@ def test_is_on_odd_level(self):
         self.assertFalse(h.is_on_odd_level(6))
         self.assertTrue(h.is_on_odd_level(7))
         self.assertTrue(h.is_on_odd_level(8))
+
+    def test_str(self):
+        h = MaxHeap([12, 14, 28, 6, 7, 18, 10, 3, 1])
+        print(h)
+
+    def test_repr(self):
+        h = MaxHeap([1, 2, 3, 4, 5])
+        print(repr(h))

tests/ds/test_MinHeap.py

@@ -5,8 +5,10 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 14/02/2016
-Updated: 05/02/2017
+
+Updated: 14/02/2017
 
 # Description
 
@@ -582,3 +584,11 @@ def test_is_on_odd_level(self):
         self.assertFalse(h.is_on_odd_level(6))
         self.assertTrue(h.is_on_odd_level(7))
         self.assertTrue(h.is_on_odd_level(8))
+
+    def test_str(self):
+        h = MinHeap([1, 2, 3, 4, 5])
+        print(h)
+
+    def test_repr(self):
+        h = MinHeap([1, 2, 3, 4, 5])
+        print(repr(h))

tests/ds/test_MinMaxHeap.py

@@ -5,8 +5,10 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 20/02/2016
-Updated: 05/02/2017
+
+Updated: 14/02/2017
 
 # Description
 
@@ -247,3 +249,11 @@ def test_index_of_min_and_max(self):
         self.assertEqual(h.index_of_max(7), -1)
         self.assertEqual(h.index_of_min(8), -1)
         self.assertEqual(h.index_of_max(8), -1)
+
+    def test_str(self):
+        h = MinMaxHeap([7, 2, 92, 67])
+        print(h)
+
+    def test_repr(self):
+        h = MinMaxHeap([7, 2, 92, 67])
+        print(repr(h))

tests/ds/test_Queue.py

@@ -6,6 +6,7 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 24/01/2017
 
 # Description

tests/ds/test_RBT.py

@@ -5,7 +5,9 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 15/02/2016
+
 Updated: 08/10/2017
 
 # Description

tests/ds/test_Stack.py

@@ -5,7 +5,9 @@
 # Meta info
 
 Author: Nelson Brochado
+
 Created: 01/07/16
+
 Updated: 04/02/2017
 
 # Description