def construct_tree(): t = LinkedBinaryTree() root = t._add_root('Trees') l = t._add_left(root, 'General trees') r = t._add_right(root, 'Binary trees') t1 = LinkedBinaryTree() root = t1._add_root('section1') left = t1._add_left(root, 'paragraph1') right = t1._add_right(root, 'paragraph2') t2 = LinkedBinaryTree() root = t2._add_root('section2') left = t2._add_left(root, 'paragraph1') right = t2._add_right(root, 'paragraph2') t._attach(l, t1, t2) return t
def construct_num_tree(): t = LinkedBinaryTree() root = t._add_root(0) l = t._add_left(root, 1) r = t._add_right(root, 2) t1 = LinkedBinaryTree() root = t1._add_root(3) left = t1._add_left(root, 5) right = t1._add_right(root, 6) t2 = LinkedBinaryTree() root = t2._add_root(4) left = t2._add_left(root, 7) right = t2._add_right(root, 8) t._attach(l, t1, t2) return t
def _compose_ht_tree(self, text): """Huffman tree construction for text.""" freq_table = self._compute_chr_freq(text) ht_queue = HeapPriorityQueue() for freq, lett in freq_table: ht_tree = LinkedBinaryTree() ht_tree._add_root((freq, lett)) ht_queue.add(freq, ht_tree) while len(ht_queue) > 1: (freq1, subtree1) = ht_queue.remove_min() (freq2, subtree2) = ht_queue.remove_min() freq = freq1 + freq2 ht_tree = LinkedBinaryTree() ht_tree._add_root((freq, None)) ht_tree._attach(ht_tree.root(), subtree1, subtree2) ht_queue.add(freq, ht_tree) _, ht_tree = ht_queue.remove_min() return ht_tree
class TestSimpleCases(unittest.TestCase): """ Test obvious cases to confirm basic functionality and syntax correctness. """ def setUp(self): self.tree = LinkedBinaryTree() # Create a proper balanced tree with 3 levels (8 elements) self.root = self.tree._add_root("Root") self.left = self.tree._add_left(self.root, "L2 left child") self.right = self.tree._add_right(self.root, "L2 right child") self.lev3_first_left = self.tree._add_left(self.left, "L3 left-1") self.tree._add_right(self.left, "L3 right-1") self.tree._add_left(self.right, "L3 left-2") self.tree._add_right(self.right, "L3 right-2") def test_validate(self): # Passing an object of type other than Position should raise TypeError with self.assertRaises(TypeError): self.tree._validate("spam") # Wrong container should raise value error position_from_other_container = LinkedBinaryTree()._add_root( "spam root") with self.assertRaises(ValueError): self.tree._validate(position_from_other_container) # If node was deprecated, meaning it was set to be its own parent per # the internal convention for deprecated nodes, then should raise # value error. p = self.lev3_first_left p._node._parent = p._node with self.assertRaises(ValueError): self.tree._validate(p) # ---------------------------------- public methods -------------------- def test_root(self): blank_tree = LinkedBinaryTree() root = blank_tree.root() self.assertEqual(root, None) # Should return None for an empty tree. root = self.tree.root() self.assertEqual(root.element(), "Root") def test_parent(self): # should return None when called on p = root parent_of_root = self.tree.parent(self.tree.root()) self.assertEqual(parent_of_root, None) parent_of_left = self.tree.parent(self.left) # Position object from # setUp, name self.left references # root's left child. self.assertEqual(parent_of_left, self.root) # Try the next level down parent_of_node = self.tree.parent(self.lev3_first_left) self.assertEqual(parent_of_node, self.left) def test_left(self): left = self.tree.left(self.root) # parent's left should be the object # stored as self.left self.assertEqual(left, self.left) def test_right(self): right = self.tree.right(self.root) # root's right should be the object # stored as self.right self.assertEqual(right, self.right) def test_num_children(self): self.assertEqual(self.tree.num_children(self.root), 2) # Root has 2 children self.assertEqual(self.tree.num_children(self.right), 2) # Right has 2 self.assertEqual(self.tree.num_children(self.lev3_first_left), 0) # This node should be in the # bottom level of the setUp # tree and therefore have # no children. # ------------------- tests for concrete methods inherited from Tree ------ def test_is_root(self): """Concrete method implemented in the Tree abstract base class and inherited through to LBT class.""" # Should be true for root self.assertTrue(self.tree.is_root(self.root)) # Should be false for a node from the middle or bottom layer self.assertFalse(self.tree.is_root(self.right)) self.assertFalse(self.tree.is_root(self.lev3_first_left)) def test_is_leaf(self): # testing _attach will "coverage" this pass def test_is_empty(self): # testing _attach will "coverage this pass def test_height(self): """ Test the height method defined in the Tree abstract base class that LBT class has through inheritance. """ # Calling it on root should return 2, the height of the full three-level # tree. self.assertEqual(self.tree.height(self.root), 2) # Height of a node in the middle layer should be 1 self.assertEqual(self.tree.height(self.right), 1) # Height of a node in the bottom layer should be 0 self.assertEqual(self.tree.height(self.lev3_first_left), 0) def test_depth(self): """ Test the depth method defined in the Tree abstract base class and inherited in the LBT class. """ # Depth of a node in the bottom later should be 2 (2 levels separating # that Position from root Position). self.assertEqual(self.tree.depth(self.lev3_first_left), 2) # Depth of node in middle layer should be 1 self.assertEqual(self.tree.depth(self.left), 1) # Depth of root should be zero self.assertEqual(self.tree.depth(self.root), 0) def test_attach(self): """Tests for the nonpublic _attach method, mainly to hit inherited public methods that it will call.""" new_tree = LinkedBinaryTree() ntroot = new_tree._add_root("New tree root") new_tree._add_left(ntroot, "NT left") new_tree._add_right(ntroot, "NT right") new_tree2 = LinkedBinaryTree() nt2root = new_tree2._add_root("2nd new tree root") new_tree2._add_left(nt2root, "left") new_tree2._add_right(nt2root, "right") self.tree._attach(self.lev3_first_left, new_tree, new_tree2) # For now just pass if none of these calls raised an error, no # unittest.assertSomething method call def test_positions(self): # This covers postorder() method for purposes # of the "coverage" metric. for position in self.tree.positions( ): # Test that they can be iterated self.assertIsInstance(position, LinkedBinaryTree.Position) # and that # they're all Positions ## def test_preorder(self): # placeholder ## pass def test_postorder(self): for position in self.tree.postorder(): self.assertIsInstance(position, LinkedBinaryTree.Position)