class BST_Test_Replace_With_10_Elements_Existing_Key(TestCase):
def setUp(self):
self._bst = BinarySearchTree()
self._bst.insert(key=5, obj=5)
self._bst.insert(key=8, obj=8)
self._bst.insert(key=7, obj=7)
self._bst.insert(key=9, obj=9)
self._bst.insert(key=10, obj=10)
self._bst.insert(key=2, obj=2)
self._bst.insert(key=1, obj=1)
self._bst.insert(key=3, obj=3)
self._bst.insert(key=4, obj=4)
self._bst.insert(key=6, obj=6)
self._bst_node_count = 10
def test_replace_with_existing_key_on_tree(self):
key_to_replace = 5
value_to_set = -5
self._bst.replace(key_to_replace, value_to_set)
self.assertEqual(
key_to_replace in self._bst, True,
'Tree has_key operation must return True for existing key')
self.assertEqual(self._bst.find(key_to_replace), value_to_set,
'Find operation failed on tree after replace')
self.assertNotEqual(self._bst.find(key_to_replace), key_to_replace,
'replaced key still exists!')
def tearDown(self):
self._bst = None
class BST_Test_Replace_Empty_Tree(TestCase):
def setUp(self):
self._bst = BinarySearchTree()
def test_replace_with_empty_tree(self):
with self.assertRaises(KeyError):
self._bst.replace('key', None)
def tearDown(self):
self._bst = None
class BSTHashBucket(collections.MutableMapping):
'''
A hash bucket is used to hold objects that hash to the same value in a hash table. This is hash
bucket using a binary search tree. This masquerades as a python dict in code where it is used.
Since bst is used as bucket datastructure, searches take O log(n) rather than O n
Note: HASHBUCKET ITERATION YIELDS KEYS. not the key value pairs in the bucket.
'''
def __init__(self):
self._bst = BinarySearchTree()
def __len__(self):
'''
The number of elements in the hash bucket
'''
return self._bst.node_count
def get(self, key, default = None):
'''
Get object associated with a key and on key miss return specified default. This is
there in Python dict and this class masquerades as dict, we implement it.
'''
try:
value = self[key]
return value
except KeyError:
return default
def __getitem__(self, key):
value = self._bst.find(key)
if value == None:
raise KeyError('Key Error: %s ' % repr(key))
return value
def __delitem__(self, key):
if key in self._bst:
self._bst.remove(key)
else:
raise KeyError('Key Error: %s ' % repr(key))
def __setitem__(self, key, obj):
if key in self._bst:
self._bst.replace(key, obj)
else:
self._bst.insert(key, obj)
def __iter__(self):
for key, value in self._bst.inorder_traversal_with_stack():
yield key
class BST_Test_Replace_With_10_Elements_Non_Existing_Key(TestCase):
def setUp(self):
self._bst = BinarySearchTree()
self._bst.insert(key=5, obj=5)
self._bst.insert(key=8, obj=8)
self._bst.insert(key=7, obj=7)
self._bst.insert(key=9, obj=9)
self._bst.insert(key=10, obj=10)
self._bst.insert(key=2, obj=2)
self._bst.insert(key=1, obj=1)
self._bst.insert(key=3, obj=3)
self._bst.insert(key=4, obj=4)
self._bst.insert(key=6, obj=6)
self._bst_node_count = 10
def test_replace_with_full_tree(self):
with self.assertRaises(KeyError):
self._bst.replace(-99, None)
def tearDown(self):
self._bst = None
print('Tree inorder traversal (key, value) pairs:')
print(traversed)
if __name__ == '__main__':
bst = BinarySearchTree()
print('Node count is %s' % str(bst.node_count))
print('Adding key value pairs (1, 1), (2, 2), .... (6, 6)')
kvpairs = [(5, 5), (2, 2), (7, 7), (1, 1), (3, 3), (9, 9), (8, 8), (4, 4),
(6, 6)]
for kvpair in kvpairs:
bst.insert(key=kvpair[0], obj=kvpair[1])
print_tree_inorder(bst)
print_tree_preorder(bst)
print_tree_postorder(bst)
#remove
element_to_remove = 9
print('removing element %s' % str(element_to_remove))
bst.remove(key=element_to_remove)
print_tree_inorder_using_stack(bst)
#replace obj for a key
key_to_replace = 1
new_object_for_Key = 111
bst.replace(key=key_to_replace, obj=new_object_for_Key)
print_tree_inorder_using_stack(bst)