TreeNode check added for heap.py

.gitignore

@@ -64,3 +64,4 @@ __pycache__/
 .idea/
 build/
 dist/
+venv/

pydatastructs/trees/heaps.py

@@ -26,7 +26,7 @@ class DHeap(Heap):
 
     elements : list, tuple
         Optional, by default 'None'.
-        List/tuple of initial elements in Heap.
+        List/tuple of initial TreeNodes in Heap.
 
     heap_property : str
         If the key stored in each node is
@@ -83,6 +83,12 @@ def __new__(cls, elements=None, heap_property="min", d=4):
             raise ValueError("%s is invalid heap property"%(heap_property))
         if elements is None:
             elements = DynamicOneDimensionalArray(TreeNode, 0)
+        else:
+            #to check if all elements provided are TreeNodes
+            check_node = map(lambda x: type(x)==type(TreeNode(1,1)),elements)
+            is_node = all(check_node)
+            if(not is_node):
+                raise TypeError("Elements have to be list/tuple of TreeNode")
         obj.heap = elements
         obj._last_pos_filled = obj.heap._last_pos_filled
         obj._build()

pydatastructs/trees/tests/test_heaps.py

@@ -29,8 +29,6 @@ def test_BinaryHeap():
     assert max_heap.extract().key == 100
 
     expected_sorted_elements = [36, 25, 19, 17, 7, 3, 2, 1]
-    l = max_heap.heap[0].left
-    l = max_heap.heap[0].right
     sorted_elements = []
     for _ in range(8):
         sorted_elements.append(max_heap.extract().key)
@@ -48,6 +46,15 @@ def test_BinaryHeap():
     sorted_elements = [min_heap.extract().key for _ in range(8)]
     assert expected_sorted_elements == sorted_elements
 
+    #To test ValueError on non TreeNode list
+    non_TreeNode_elements = [
+                (7, 7), TreeNode(25, 25), TreeNode(100, 100),
+                TreeNode(1, 1), (2, 2), TreeNode(3, 3),
+                TreeNode(17, 17), TreeNode(19, 19), TreeNode(36, 36)
+            ]
+    assert raises(TypeError, lambda:
+                BinaryHeap(elements = non_TreeNode_elements, heap_property='min'))
+
 def test_TernaryHeap():
     max_heap = TernaryHeap(heap_property="max")
     assert max_heap.extract() is None