From c0122316d16f0d4ba7c45d5a8089e4658dd36beb Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Thu, 19 Feb 2015 14:57:38 -0800
Subject: [PATCH 01/20] first draft of depth first traversal

---
 graph/simple_graph.py      | 15 +++++++++++++++
 graph/test_simple_graph.py | 22 ++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 7aee42c..058f324 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -1,3 +1,5 @@
+from collections import OrderedDict
+
 class Graph(object):
     """Implements a graph data structure"""
 
@@ -69,3 +71,16 @@ def adjacent(self, node_1, node_2):
             return node_2 in self.graph_dict[node_1]
         except KeyError:
             raise KeyError("First node not found")
+
+    def depth_first_traversal(self, start):
+        explored = OrderedDict()
+        return self._depth_first_traversal(start, explored)
+
+    def _depth_first_traversal(self, start, explored):
+        explored.setdefault(start, 1)
+
+        for child in self.graph_dict[start]:
+            if child not in explored:
+                self._depth_first_traversal(child, explored)
+
+        return explored.keys()
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index 01bbb10..87447f5 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -15,6 +15,23 @@ def test_graph():
     return test_graph
 
 
+@pytest.fixture(scope="function")
+def test_traversal_graph():
+    test_graph = Graph()
+    for i in range(10):
+        test_graph.add_node(i)
+    test_graph.add_edge(0, 1)
+    test_graph.add_edge(0, 2)
+    test_graph.add_edge(0, 3)
+    test_graph.add_edge(1, 4)
+    test_graph.add_edge(1, 5)
+    test_graph.add_edge(1, 8)
+    test_graph.add_edge(5, 6)
+    test_graph.add_edge(6, 7)
+    test_graph.add_edge(2, 9)
+
+    return test_graph
+
 def test_constructor():
     test = Graph()
     assert test.graph_dict == {}
@@ -128,3 +145,8 @@ def test_adjacent_second_node_not_found(test_graph):
     with pytest.raises(KeyError) as e:
         test_graph.adjacent("test", 47)
     assert 'Second node not found' in str(e.value)
+
+
+def test_depth_first(test_traversal_graph):
+    assert test_traversal_graph.depth_first_traversal(0) == [
+        0, 1, 4, 5, 6, 7, 8, 2, 9, 3]

From a0ccc2971940f55bd3ea14548d24b3926836c2ce Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Thu, 19 Feb 2015 15:11:25 -0800
Subject: [PATCH 02/20] adds test for unconnected graph and cyclic graph

---
 graph/test_simple_graph.py | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index 87447f5..ffd501a 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -147,6 +147,37 @@ def test_adjacent_second_node_not_found(test_graph):
     assert 'Second node not found' in str(e.value)
 
 
-def test_depth_first(test_traversal_graph):
+def test_depth_first_from_node_0(test_traversal_graph):
     assert test_traversal_graph.depth_first_traversal(0) == [
         0, 1, 4, 5, 6, 7, 8, 2, 9, 3]
+
+
+def test_depth_first_from_node_1(test_traversal_graph):
+    assert test_traversal_graph.depth_first_traversal(1) == [
+        1, 4, 5, 6, 7, 8]
+
+
+def test_depth_first_no_edges():
+    test = Graph()
+    test.add_node(55)
+    test.add_node("test")
+    test.add_node(2)
+    assert test.depth_first_traversal(55) == [55]
+
+
+def test_depth_multiple_edges():
+    test = Graph()
+    for i in range(5):
+        test.add_node(i)
+    test.add_edge(0, 1)
+    test.add_edge(0, 2)
+    test.add_edge(1, 2)
+    test.add_edge(1, 3)
+    test.add_edge(2, 3)
+    test.add_edge(3, 4)
+
+    assert test.depth_first_traversal(0) == [0, 1, 2, 3, 4]
+
+
+def test_depth_cyclic(test_graph):
+    assert test_graph.depth_first_traversal(5) == [5, 42, "test"]

From 67a1b26debe453667407e06ef2bb277e24819a78 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Thu, 19 Feb 2015 15:48:47 -0800
Subject: [PATCH 03/20] adds first draft of breadth first traversal

---
 graph/simple_graph.py      | 85 ++++++++++++++++++++++++++++++++++++++
 graph/test_simple_graph.py | 36 +++++++++++++---
 2 files changed, 116 insertions(+), 5 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 058f324..0d82610 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -1,4 +1,6 @@
 from collections import OrderedDict
+# import Queue
+
 
 class Graph(object):
     """Implements a graph data structure"""
@@ -84,3 +86,86 @@ def _depth_first_traversal(self, start, explored):
                 self._depth_first_traversal(child, explored)
 
         return explored.keys()
+
+    def breadth_first_traversal(self, start):
+        explored = OrderedDict()
+        queue = Queue()
+        explored.setdefault(start, 1)
+
+        queue.enqueue(start)
+
+        while queue.size():
+            node = queue.dequeue()
+
+            for child in self.graph_dict[node]:
+                if child not in explored:
+                    explored.setdefault(child, 1)
+                    queue.enqueue(child)
+
+        return explored.keys()
+
+   
+
+
+
+
+
+class Queue(object):
+    """Implement a queue data structure"""
+    def __init__(self):
+        self.front = None
+        self.back = None
+
+    def __iter__(self):
+        current = self.front
+        while current:
+            yield current
+            current = current.next_item
+
+    def enqueue(self, val):
+        """Take item value, add to the back of the queue"""
+        new_item = Item(val)
+        try:
+            self.back.next_item = new_item
+        except AttributeError:
+            self.front = new_item
+        self.back = new_item
+
+    def dequeue(self):
+        """Remove the front item from the queue and return its value"""
+
+        prevFront = self.front
+        try:
+            self.front = self.front.next_item
+            if self.front is None:
+                self.back = self.front
+        except AttributeError:
+            raise AttributeError("The queue is empty")
+        return prevFront.val
+
+    def size(self):
+        count = 0
+        for _ in self:
+            count += 1
+
+        return count
+
+
+class Item(object):
+
+    def __init__(self, val, next_item=None):
+        self.val = val
+        self.next_item = next_item
+
+     # def _breadth_first_traversal(self, start, explored):
+     #    explored.setdefault(start, 1)
+
+     #    for child in self.graph_dict[start]:
+     #        if child not in explored:
+     #            self._depth_first_traversal(child, explored)
+
+     #    return explored.keys()
+
+
+
+
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index ffd501a..3dba5b9 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -16,7 +16,7 @@ def test_graph():
 
 
 @pytest.fixture(scope="function")
-def test_traversal_graph():
+def test_depth_traversal_graph():
     test_graph = Graph()
     for i in range(10):
         test_graph.add_node(i)
@@ -32,6 +32,24 @@ def test_traversal_graph():
 
     return test_graph
 
+
+@pytest.fixture(scope="function")
+def test_breadth_traversal_graph():
+    test_graph = Graph()
+    for i in range(1, 10):
+        test_graph.add_node(i)
+    test_graph.add_edge(1, 2)
+    test_graph.add_edge(1, 3)
+    test_graph.add_edge(1, 4)
+    test_graph.add_edge(2, 5)
+    test_graph.add_edge(2, 6)
+    test_graph.add_edge(4, 7)
+    test_graph.add_edge(4, 8)
+    test_graph.add_edge(5, 9)
+
+    return test_graph
+
+
 def test_constructor():
     test = Graph()
     assert test.graph_dict == {}
@@ -147,13 +165,13 @@ def test_adjacent_second_node_not_found(test_graph):
     assert 'Second node not found' in str(e.value)
 
 
-def test_depth_first_from_node_0(test_traversal_graph):
-    assert test_traversal_graph.depth_first_traversal(0) == [
+def test_depth_first_from_node_0(test_depth_traversal_graph):
+    assert test_depth_traversal_graph.depth_first_traversal(0) == [
         0, 1, 4, 5, 6, 7, 8, 2, 9, 3]
 
 
-def test_depth_first_from_node_1(test_traversal_graph):
-    assert test_traversal_graph.depth_first_traversal(1) == [
+def test_depth_first_from_node_1(test_depth_traversal_graph):
+    assert test_depth_traversal_graph.depth_first_traversal(1) == [
         1, 4, 5, 6, 7, 8]
 
 
@@ -181,3 +199,11 @@ def test_depth_multiple_edges():
 
 def test_depth_cyclic(test_graph):
     assert test_graph.depth_first_traversal(5) == [5, 42, "test"]
+
+
+def test_breadth_first(test_breadth_traversal_graph):
+    assert test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10)
+
+
+
+

From fa2602a5e082a57351509b7cacdaacff8f443496 Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Thu, 19 Feb 2015 16:00:11 -0800
Subject: [PATCH 04/20] importing Queue

---
 __init__.py           |  0
 graph/__init__.py     |  0
 graph/simple_graph.py | 71 ++-----------------------------------------
 3 files changed, 2 insertions(+), 69 deletions(-)
 create mode 100644 __init__.py
 create mode 100644 graph/__init__.py

diff --git a/__init__.py b/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/graph/__init__.py b/graph/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 0d82610..ce43d4c 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -1,6 +1,5 @@
 from collections import OrderedDict
-# import Queue
-
+from queue import Queue
 
 class Graph(object):
     """Implements a graph data structure"""
@@ -20,7 +19,7 @@ def edges(self):
 
     def add_node(self, node):
         """add a new node 'n' to the graph"""
-        self.graph_dict.setdefault(node,[])
+        self.graph_dict.setdefault(node, [])
 
     def add_edge(self, node_1, node_2):
         """add a new edge to the graph connecting 'n1' and 'n2', if either n1
@@ -103,69 +102,3 @@ def breadth_first_traversal(self, start):
                     queue.enqueue(child)
 
         return explored.keys()
-
-   
-
-
-
-
-
-class Queue(object):
-    """Implement a queue data structure"""
-    def __init__(self):
-        self.front = None
-        self.back = None
-
-    def __iter__(self):
-        current = self.front
-        while current:
-            yield current
-            current = current.next_item
-
-    def enqueue(self, val):
-        """Take item value, add to the back of the queue"""
-        new_item = Item(val)
-        try:
-            self.back.next_item = new_item
-        except AttributeError:
-            self.front = new_item
-        self.back = new_item
-
-    def dequeue(self):
-        """Remove the front item from the queue and return its value"""
-
-        prevFront = self.front
-        try:
-            self.front = self.front.next_item
-            if self.front is None:
-                self.back = self.front
-        except AttributeError:
-            raise AttributeError("The queue is empty")
-        return prevFront.val
-
-    def size(self):
-        count = 0
-        for _ in self:
-            count += 1
-
-        return count
-
-
-class Item(object):
-
-    def __init__(self, val, next_item=None):
-        self.val = val
-        self.next_item = next_item
-
-     # def _breadth_first_traversal(self, start, explored):
-     #    explored.setdefault(start, 1)
-
-     #    for child in self.graph_dict[start]:
-     #        if child not in explored:
-     #            self._depth_first_traversal(child, explored)
-
-     #    return explored.keys()
-
-
-
-

From 397dd51ebd2bb822a0f602f9a9c2bde08b08b040 Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Thu, 19 Feb 2015 16:13:49 -0800
Subject: [PATCH 05/20] added exception handling to breadth_first, and tests

---
 graph/simple_graph.py      | 26 +++++++++++++++-----------
 graph/test_simple_graph.py |  6 ++++++
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index ce43d4c..985ef31 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -1,6 +1,7 @@
 from collections import OrderedDict
 from queue import Queue
 
+
 class Graph(object):
     """Implements a graph data structure"""
 
@@ -87,18 +88,21 @@ def _depth_first_traversal(self, start, explored):
         return explored.keys()
 
     def breadth_first_traversal(self, start):
-        explored = OrderedDict()
-        queue = Queue()
-        explored.setdefault(start, 1)
+        try:
+            explored = OrderedDict()
+            queue = Queue()
+            explored.setdefault(start, 1)
 
-        queue.enqueue(start)
+            queue.enqueue(start)
 
-        while queue.size():
-            node = queue.dequeue()
+            while queue.size():
+                node = queue.dequeue()
 
-            for child in self.graph_dict[node]:
-                if child not in explored:
-                    explored.setdefault(child, 1)
-                    queue.enqueue(child)
+                for child in self.graph_dict[node]:
+                    if child not in explored:
+                        explored.setdefault(child, 1)
+                        queue.enqueue(child)
 
-        return explored.keys()
+            return explored.keys()
+        except KeyError:
+            raise KeyError("Node does not exist")
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index 3dba5b9..301413e 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -205,5 +205,11 @@ def test_breadth_first(test_breadth_traversal_graph):
     assert test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10)
 
 
+def test_breadth_first_from_node_3(test_breadth_traversal_graph):
+    assert test_breadth_traversal_graph.breadth_first_traversal(3) == [3]
 
 
+def test_breadth_first_from_non_existent_node(test_breadth_traversal_graph):
+    with pytest.raises(KeyError) as e:
+        test_breadth_traversal_graph.breadth_first_traversal(11)
+    assert "Node does not exist" in str(e.value)

From 15c45ade1531106f9bda214f0ed621ad1e8f584e Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Thu, 19 Feb 2015 16:38:03 -0800
Subject: [PATCH 06/20] Docstrings added, README.md updated

---
 README.md                  |  2 ++
 graph/simple_graph.py      | 14 ++++++++++++--
 graph/test_simple_graph.py | 35 ++++++++++++++++++++++++++++++++++-
 3 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index ccf9f80..2332352 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,8 @@ This repository holds sample code for a number of classic data structures implem
 
 * Graph (unweighted, directed)
     -  As described from [Python Patterns - Implementing Graphs](https://www.python.org/doc/essays/graphs/) "Graphs are networks consisting of nodes connected by edges or arcs. In directed graphs, the connections between nodes have a direction, and are called arcs."
+    - Graph Traversal
+        - Graph traversal is explored in a [depth first](http://en.wikipedia.org/wiki/Depth-first_search) and [breadth first](http://en.wikipedia.org/wiki/Breadth-first_search) style.
 
 ## Resources
 [Linked Lists Wiki](http://en.wikipedia.org/wiki/Linked_list)  
diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 985ef31..2cc2f47 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -75,10 +75,17 @@ def adjacent(self, node_1, node_2):
             raise KeyError("First node not found")
 
     def depth_first_traversal(self, start):
-        explored = OrderedDict()
-        return self._depth_first_traversal(start, explored)
+        """Perform a full depth-first traversal of the graph beginning at start.
+        Return the full visited path when traversal is complete.
+        """
+        try:
+            explored = OrderedDict()
+            return self._depth_first_traversal(start, explored)
+        except KeyError:
+            raise KeyError("Node does not exist")
 
     def _depth_first_traversal(self, start, explored):
+        """Helper function for depth_first_traversal for recursion"""
         explored.setdefault(start, 1)
 
         for child in self.graph_dict[start]:
@@ -88,6 +95,9 @@ def _depth_first_traversal(self, start, explored):
         return explored.keys()
 
     def breadth_first_traversal(self, start):
+        """Perform a full breadth-first traversal of the graph, beginning at
+        start. Return the full visited path when traversal is complete.
+        """
         try:
             explored = OrderedDict()
             queue = Queue()
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index 301413e..2c7e24a 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -197,12 +197,19 @@ def test_depth_multiple_edges():
     assert test.depth_first_traversal(0) == [0, 1, 2, 3, 4]
 
 
+def test_depth_first_from_non_existent_node(test_depth_traversal_graph):
+    with pytest.raises(KeyError) as e:
+        test_depth_traversal_graph.depth_first_traversal(11)
+    assert "Node does not exist" in str(e.value)
+
+
 def test_depth_cyclic(test_graph):
     assert test_graph.depth_first_traversal(5) == [5, 42, "test"]
 
 
 def test_breadth_first(test_breadth_traversal_graph):
-    assert test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10)
+    assert (
+        test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10))
 
 
 def test_breadth_first_from_node_3(test_breadth_traversal_graph):
@@ -213,3 +220,29 @@ def test_breadth_first_from_non_existent_node(test_breadth_traversal_graph):
     with pytest.raises(KeyError) as e:
         test_breadth_traversal_graph.breadth_first_traversal(11)
     assert "Node does not exist" in str(e.value)
+
+
+def test_breadth_cyclic(test_graph):
+    assert test_graph.breadth_first_traversal(5) == [5, 42, "test"]
+
+
+def test_breadth_first_no_edges():
+    test = Graph()
+    test.add_node(55)
+    test.add_node("test")
+    test.add_node(2)
+    assert test.breadth_first_traversal(55) == [55]
+
+
+def test_breadth_multiple_edges():
+    test = Graph()
+    for i in range(5):
+        test.add_node(i)
+    test.add_edge(0, 1)
+    test.add_edge(0, 2)
+    test.add_edge(1, 2)
+    test.add_edge(1, 3)
+    test.add_edge(2, 3)
+    test.add_edge(3, 4)
+
+    assert test.breadth_first_traversal(0) == [0, 1, 2, 3, 4]

From a9b6ea63d4c6781ae3e66f3dc1eb269ca674dbb9 Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Mon, 2 Mar 2015 13:41:08 -0800
Subject: [PATCH 07/20] changed add_node to dictionary. add_edge now has weight

---
 graph/simple_graph.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 2cc2f47..6aeede8 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -2,6 +2,8 @@
 from queue import Queue
 
 
+W_DEFAULT = 1
+
 class Graph(object):
     """Implements a graph data structure"""
 
@@ -20,14 +22,14 @@ def edges(self):
 
     def add_node(self, node):
         """add a new node 'n' to the graph"""
-        self.graph_dict.setdefault(node, [])
+        self.graph_dict.setdefault(node, {})
 
-    def add_edge(self, node_1, node_2):
+    def add_edge(self, node_1, node_2, weight=W_DEFAULT):
         """add a new edge to the graph connecting 'n1' and 'n2', if either n1
         or n2 are not already present in the graph, they are added.
         """
         try:
-            self.graph_dict[node_1].append(node_2)
+            self.graph_dict[node_1][node_2] = weight
         except KeyError:
             self.add_node(node_1)
             self.graph_dict[node_1].append(node_2)

From b1f0eddc9df6e3f8f9ef5e9f8ab2b6141c4e7d9d Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Mon, 2 Mar 2015 13:54:26 -0800
Subject: [PATCH 08/20] changed the del_node method to delete a dict, same with
 del_edge

---
 graph/simple_graph.py | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 6aeede8..af95985 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -40,20 +40,19 @@ def del_node(self, node):
         """delete the node 'n' from the graph"""
         try:
             del self.graph_dict[node]
-            for val_list in self.graph_dict.values():
-                if node in val_list:
-                    val_list.remove(node)
+            for val_dict in self.graph_dict.values():
+                if node in val_dict:
+                    del val_dict[node]
         except KeyError:
             raise KeyError("Node not found")
 
     def del_edge(self, node_1, node_2):
         """delete the edge connecting 'n1' and 'n2' from the graph"""
         try:
-            self.graph_dict[node_1].remove(node_2)
+            del self.graph_dict[node_1][node_2]
         except KeyError:
-            raise KeyError("First node not found")
-        except ValueError:
-            raise ValueError("Edge not found")
+            raise KeyError("Edge not found")
+        
 
     def has_node(self, node):
         """True if node 'n' is contained in the graph, False if not"""

From 5e0604c4d21cab5c9eb903585b43399fb7cf4a70 Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Mon, 2 Mar 2015 13:55:47 -0800
Subject: [PATCH 09/20] linting

---
 graph/simple_graph.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index af95985..7d12204 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -4,6 +4,7 @@
 
 W_DEFAULT = 1
 
+
 class Graph(object):
     """Implements a graph data structure"""
 
@@ -52,7 +53,6 @@ def del_edge(self, node_1, node_2):
             del self.graph_dict[node_1][node_2]
         except KeyError:
             raise KeyError("Edge not found")
-        
 
     def has_node(self, node):
         """True if node 'n' is contained in the graph, False if not"""

From bc25ce7731f6ae1c82a3462ed31ba84234b12a62 Mon Sep 17 00:00:00 2001
From: poolbath1 <eyftickid@poolbath1.33mail.com>
Date: Mon, 2 Mar 2015 14:15:07 -0800
Subject: [PATCH 10/20] changing tests to use dicts

---
 graph/simple_graph.py      | 4 ++--
 graph/test_simple_graph.py | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 7d12204..ca7ad43 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -33,7 +33,7 @@ def add_edge(self, node_1, node_2, weight=W_DEFAULT):
             self.graph_dict[node_1][node_2] = weight
         except KeyError:
             self.add_node(node_1)
-            self.graph_dict[node_1].append(node_2)
+            self.graph_dict[node_1][node_2] = weight
         if node_2 not in self.nodes():
             self.add_node(node_2)
 
@@ -59,7 +59,7 @@ def has_node(self, node):
         return node in self.graph_dict
 
     def neighbors(self, node):
-        """return the list of all nodes connected to 'n' by edges"""
+        """return the dict of all nodes connected to 'n' by edges"""
         try:
             return self.graph_dict[node]
         except KeyError:
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index 2c7e24a..2c0916d 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -120,7 +120,7 @@ def test_del_edge(test_graph):
 
 
 def test_del_edge_not_found(test_graph):
-    with pytest.raises(ValueError) as e:
+    with pytest.raises(KeyError) as e:
         test_graph.del_edge(5, "test")
     assert "Edge not found" in str(e.value)
 
@@ -128,7 +128,7 @@ def test_del_edge_not_found(test_graph):
 def test_del_edge_node_not_found(test_graph):
     with pytest.raises(KeyError) as e:
         test_graph.del_edge(8, "test")
-    assert "First node not found" in str(e.value)
+    assert "Edge not found" in str(e.value)
 
 
 def test_has_node_true(test_graph):
@@ -140,7 +140,7 @@ def test_has_node_false(test_graph):
 
 
 def test_neighbors(test_graph):
-    assert test_graph.neighbors(5) == [42]
+    assert test_graph.neighbors(5) == {42: 1}
 
 
 def test_neighbors_not_found(test_graph):

From 241ad51c0d2337e61ff332669bf8935ff8daa460 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 14:38:31 -0800
Subject: [PATCH 11/20] converts edge dict to ordered dict to maintain
 predictable order in traversals

---
 graph/simple_graph.py      |  2 +-
 graph/test_simple_graph.py | 49 +++-----------------------------------
 2 files changed, 4 insertions(+), 47 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index ca7ad43..ccc87e5 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -23,7 +23,7 @@ def edges(self):
 
     def add_node(self, node):
         """add a new node 'n' to the graph"""
-        self.graph_dict.setdefault(node, {})
+        self.graph_dict.setdefault(node, OrderedDict())
 
     def add_edge(self, node_1, node_2, weight=W_DEFAULT):
         """add a new edge to the graph connecting 'n1' and 'n2', if either n1
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index 2c0916d..b4be4f6 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -1,6 +1,6 @@
 import pytest
 from simple_graph import Graph
-
+from collections import OrderedDict
 
 @pytest.fixture(scope="function")
 def test_graph():
@@ -140,7 +140,7 @@ def test_has_node_false(test_graph):
 
 
 def test_neighbors(test_graph):
-    assert test_graph.neighbors(5) == {42: 1}
+    assert test_graph.neighbors(5) == OrderedDict([(42, 1)])
 
 
 def test_neighbors_not_found(test_graph):
@@ -197,52 +197,9 @@ def test_depth_multiple_edges():
     assert test.depth_first_traversal(0) == [0, 1, 2, 3, 4]
 
 
-def test_depth_first_from_non_existent_node(test_depth_traversal_graph):
-    with pytest.raises(KeyError) as e:
-        test_depth_traversal_graph.depth_first_traversal(11)
-    assert "Node does not exist" in str(e.value)
-
-
 def test_depth_cyclic(test_graph):
     assert test_graph.depth_first_traversal(5) == [5, 42, "test"]
 
 
 def test_breadth_first(test_breadth_traversal_graph):
-    assert (
-        test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10))
-
-
-def test_breadth_first_from_node_3(test_breadth_traversal_graph):
-    assert test_breadth_traversal_graph.breadth_first_traversal(3) == [3]
-
-
-def test_breadth_first_from_non_existent_node(test_breadth_traversal_graph):
-    with pytest.raises(KeyError) as e:
-        test_breadth_traversal_graph.breadth_first_traversal(11)
-    assert "Node does not exist" in str(e.value)
-
-
-def test_breadth_cyclic(test_graph):
-    assert test_graph.breadth_first_traversal(5) == [5, 42, "test"]
-
-
-def test_breadth_first_no_edges():
-    test = Graph()
-    test.add_node(55)
-    test.add_node("test")
-    test.add_node(2)
-    assert test.breadth_first_traversal(55) == [55]
-
-
-def test_breadth_multiple_edges():
-    test = Graph()
-    for i in range(5):
-        test.add_node(i)
-    test.add_edge(0, 1)
-    test.add_edge(0, 2)
-    test.add_edge(1, 2)
-    test.add_edge(1, 3)
-    test.add_edge(2, 3)
-    test.add_edge(3, 4)
-
-    assert test.breadth_first_traversal(0) == [0, 1, 2, 3, 4]
+    assert test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10)

From 214c882eafa7a5ddefde92eaea6d391fbadd26f2 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 14:47:37 -0800
Subject: [PATCH 12/20] adds travis and updates readme with weighted graph

---
 .travis.yml | 4 ++++
 README.md   | 5 +++++
 2 files changed, 9 insertions(+)
 create mode 100644 .travis.yml

diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..6eebfa7
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,4 @@
+language: python
+python:
+    - "2.7"
+install: pip install -r requirements.txt
\ No newline at end of file
diff --git a/README.md b/README.md
index 2332352..916c790 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,8 @@ This repository holds sample code for a number of classic data structures implem
     -  As described from [Python Patterns - Implementing Graphs](https://www.python.org/doc/essays/graphs/) "Graphs are networks consisting of nodes connected by edges or arcs. In directed graphs, the connections between nodes have a direction, and are called arcs."
     - Graph Traversal
         - Graph traversal is explored in a [depth first](http://en.wikipedia.org/wiki/Depth-first_search) and [breadth first](http://en.wikipedia.org/wiki/Breadth-first_search) style.
+    - Graph weighting
+        - Edges accept value weights or default to one if none is provided
 
 ## Resources
 [Linked Lists Wiki](http://en.wikipedia.org/wiki/Linked_list)  
@@ -35,6 +37,9 @@ This repository holds sample code for a number of classic data structures implem
 
 
 Pytest - for testing structure functions
+Travis CI
+[![Build Status](https://travis-ci.org/henrykh/data-structures.svg)](https://travis-ci.org/henrykh/data-structures)
+
 
 ##Collaborators
 Joel Stanner  

From 58ae7b93efa25d3c8e6f432cdb53398f900f30c9 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 14:48:23 -0800
Subject: [PATCH 13/20] edit travis yml

---
 .travis.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 6eebfa7..cd82378 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,5 @@
 language: python
 python:
     - "2.7"
-install: pip install -r requirements.txt
\ No newline at end of file
+install: pip install -r requirements.txt
+script: py.test
\ No newline at end of file

From 9cf442e27d2b76be80bcf9f65f2f1a1d480088e6 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 14:50:56 -0800
Subject: [PATCH 14/20] removes pip install requirements from travis, edits
 readme

---
 .travis.yml | 1 -
 README.md   | 3 ++-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index cd82378..38e8f2d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,4 @@
 language: python
 python:
     - "2.7"
-install: pip install -r requirements.txt
 script: py.test
\ No newline at end of file
diff --git a/README.md b/README.md
index 916c790..8f49e76 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,5 @@
+[![Build Status](https://travis-ci.org/henrykh/data-structures.svg)](https://travis-ci.org/henrykh/data-structures)  
+
 # data-structures
 
 This repository holds sample code for a number of classic data structures implemented in Python.
@@ -38,7 +40,6 @@ This repository holds sample code for a number of classic data structures implem
 
 Pytest - for testing structure functions
 Travis CI
-[![Build Status](https://travis-ci.org/henrykh/data-structures.svg)](https://travis-ci.org/henrykh/data-structures)
 
 
 ##Collaborators

From 5a65d5b9053fa9165522ece4d92e879b5f57e35d Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 14:59:13 -0800
Subject: [PATCH 15/20] adds tests for adding edges

---
 graph/test_simple_graph.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index b4be4f6..d1ed51e 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -203,3 +203,15 @@ def test_depth_cyclic(test_graph):
 
 def test_breadth_first(test_breadth_traversal_graph):
     assert test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10)
+
+
+def test_add_edge_with_default_weight():
+    test = Graph()
+    test.add_edge(1, 2)
+    assert test.graph_dict[1] == OrderedDict([(2, 1)])
+
+
+def test_add_edge_with_weight_parameter():
+    test = Graph()
+    test.add_edge(1, 2, 10000)
+    assert test.graph_dict[1] == OrderedDict([(2, 10000)])

From c10bfe40ad5f2162edde1827219c8be43ea91f3e Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 15:27:10 -0800
Subject: [PATCH 16/20] edges method gives edge weights

---
 graph/simple_graph.py | 42 +++++++++++++++++++++---------------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index ccc87e5..86e1735 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -1,5 +1,5 @@
 from collections import OrderedDict
-from queue import Queue
+# from queue import Queue
 
 
 W_DEFAULT = 1
@@ -18,8 +18,8 @@ def nodes(self):
     def edges(self):
         """return a list of all edges in the graph"""
 
-        return [(key, node) for key, value in
-                self.graph_dict.iteritems() for node in value]
+        return [(key, node, weight) for key, edge_dict in
+                self.graph_dict.iteritems() for node, weight in edge_dict.items()]
 
     def add_node(self, node):
         """add a new node 'n' to the graph"""
@@ -95,25 +95,25 @@ def _depth_first_traversal(self, start, explored):
 
         return explored.keys()
 
-    def breadth_first_traversal(self, start):
-        """Perform a full breadth-first traversal of the graph, beginning at
-        start. Return the full visited path when traversal is complete.
-        """
-        try:
-            explored = OrderedDict()
-            queue = Queue()
-            explored.setdefault(start, 1)
+    # def breadth_first_traversal(self, start):
+    #     """Perform a full breadth-first traversal of the graph, beginning at
+    #     start. Return the full visited path when traversal is complete.
+    #     """
+    #     try:
+    #         explored = OrderedDict()
+    #         queue = Queue()
+    #         explored.setdefault(start, 1)
 
-            queue.enqueue(start)
+    #         queue.enqueue(start)
 
-            while queue.size():
-                node = queue.dequeue()
+    #         while queue.size():
+    #             node = queue.dequeue()
 
-                for child in self.graph_dict[node]:
-                    if child not in explored:
-                        explored.setdefault(child, 1)
-                        queue.enqueue(child)
+    #             for child in self.graph_dict[node]:
+    #                 if child not in explored:
+    #                     explored.setdefault(child, 1)
+    #                     queue.enqueue(child)
 
-            return explored.keys()
-        except KeyError:
-            raise KeyError("Node does not exist")
+    #         return explored.keys()
+    #     except KeyError:
+    #         raise KeyError("Node does not exist")

From 0bd6e10605c5aabe068d55c4f36eae97e0f7c535 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Mon, 2 Mar 2015 15:29:38 -0800
Subject: [PATCH 17/20] updates test for edges method

---
 graph/simple_graph.py      | 38 +++++++++++++++++++-------------------
 graph/test_simple_graph.py | 28 ++++++++++++++--------------
 2 files changed, 33 insertions(+), 33 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 86e1735..85a796f 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -1,5 +1,5 @@
 from collections import OrderedDict
-# from queue import Queue
+from queue import Queue
 
 
 W_DEFAULT = 1
@@ -95,25 +95,25 @@ def _depth_first_traversal(self, start, explored):
 
         return explored.keys()
 
-    # def breadth_first_traversal(self, start):
-    #     """Perform a full breadth-first traversal of the graph, beginning at
-    #     start. Return the full visited path when traversal is complete.
-    #     """
-    #     try:
-    #         explored = OrderedDict()
-    #         queue = Queue()
-    #         explored.setdefault(start, 1)
+    def breadth_first_traversal(self, start):
+        """Perform a full breadth-first traversal of the graph, beginning at
+        start. Return the full visited path when traversal is complete.
+        """
+        try:
+            explored = OrderedDict()
+            queue = Queue()
+            explored.setdefault(start, 1)
 
-    #         queue.enqueue(start)
+            queue.enqueue(start)
 
-    #         while queue.size():
-    #             node = queue.dequeue()
+            while queue.size():
+                node = queue.dequeue()
 
-    #             for child in self.graph_dict[node]:
-    #                 if child not in explored:
-    #                     explored.setdefault(child, 1)
-    #                     queue.enqueue(child)
+                for child in self.graph_dict[node]:
+                    if child not in explored:
+                        explored.setdefault(child, 1)
+                        queue.enqueue(child)
 
-    #         return explored.keys()
-    #     except KeyError:
-    #         raise KeyError("Node does not exist")
+            return explored.keys()
+        except KeyError:
+            raise KeyError("Node does not exist")
diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index d1ed51e..f661639 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -9,7 +9,7 @@ def test_graph():
     test_graph.add_node(42)
     test_graph.add_node("test")
     test_graph.add_edge(5, 42)
-    test_graph.add_edge(42, "test")
+    test_graph.add_edge(42, "test", 1000)
     test_graph.add_edge("test", 5)
 
     return test_graph
@@ -91,12 +91,24 @@ def test_add_edge_second_node_new():
     assert "test" in test.graph_dict[55]
 
 
+def test_add_edge_with_default_weight():
+    test = Graph()
+    test.add_edge(1, 2)
+    assert test.graph_dict[1] == OrderedDict([(2, 1)])
+
+
+def test_add_edge_with_weight_parameter():
+    test = Graph()
+    test.add_edge(1, 2, 10000)
+    assert test.graph_dict[1] == OrderedDict([(2, 10000)])
+
+
 def test_nodes(test_graph):
     assert test_graph.nodes() == ["test", 42, 5]
 
 
 def test_edges(test_graph):
-    assert test_graph.edges() == [("test", 5), (42, "test"), (5, 42)]
+    assert test_graph.edges() == [("test", 5, 1), (42, "test", 1000), (5, 42, 1)]
 
 
 def test_del_node(test_graph):
@@ -203,15 +215,3 @@ def test_depth_cyclic(test_graph):
 
 def test_breadth_first(test_breadth_traversal_graph):
     assert test_breadth_traversal_graph.breadth_first_traversal(1) == range(1, 10)
-
-
-def test_add_edge_with_default_weight():
-    test = Graph()
-    test.add_edge(1, 2)
-    assert test.graph_dict[1] == OrderedDict([(2, 1)])
-
-
-def test_add_edge_with_weight_parameter():
-    test = Graph()
-    test.add_edge(1, 2, 10000)
-    assert test.graph_dict[1] == OrderedDict([(2, 10000)])

From 47e5f871d7ce9ee5997ba4df4c6602b5c54bab79 Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Tue, 3 Mar 2015 09:52:21 -0800
Subject: [PATCH 18/20] updates add edge, neighbors now returns a list

---
 graph/simple_graph.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index 85a796f..b6eb087 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -30,12 +30,11 @@ def add_edge(self, node_1, node_2, weight=W_DEFAULT):
         or n2 are not already present in the graph, they are added.
         """
         try:
+            self.add_node(node_2)
             self.graph_dict[node_1][node_2] = weight
         except KeyError:
             self.add_node(node_1)
             self.graph_dict[node_1][node_2] = weight
-        if node_2 not in self.nodes():
-            self.add_node(node_2)
 
     def del_node(self, node):
         """delete the node 'n' from the graph"""
@@ -59,9 +58,9 @@ def has_node(self, node):
         return node in self.graph_dict
 
     def neighbors(self, node):
-        """return the dict of all nodes connected to 'n' by edges"""
+        """return the list of all nodes connected to 'n' by edges"""
         try:
-            return self.graph_dict[node]
+            return self.graph_dict[node].keys()
         except KeyError:
             raise KeyError("Node not found")
 

From 31a5339f5ddf5c47582eca724e6f9d303eb3d43d Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Tue, 3 Mar 2015 16:26:27 -0800
Subject: [PATCH 19/20] fixes neighbors test to check a list

---
 graph/test_simple_graph.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/graph/test_simple_graph.py b/graph/test_simple_graph.py
index f661639..2bb61f0 100644
--- a/graph/test_simple_graph.py
+++ b/graph/test_simple_graph.py
@@ -152,7 +152,7 @@ def test_has_node_false(test_graph):
 
 
 def test_neighbors(test_graph):
-    assert test_graph.neighbors(5) == OrderedDict([(42, 1)])
+    assert test_graph.neighbors(5) == [42]
 
 
 def test_neighbors_not_found(test_graph):

From 00b6a7d14613f4b2c23951c87c8505dc55fb912f Mon Sep 17 00:00:00 2001
From: henrykh <henryhowes@gmail.com>
Date: Wed, 4 Mar 2015 16:48:34 -0800
Subject: [PATCH 20/20] adds iteritems to edge_dict in edges()

---
 graph/simple_graph.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/graph/simple_graph.py b/graph/simple_graph.py
index b6eb087..1dd5df9 100644
--- a/graph/simple_graph.py
+++ b/graph/simple_graph.py
@@ -19,7 +19,8 @@ def edges(self):
         """return a list of all edges in the graph"""
 
         return [(key, node, weight) for key, edge_dict in
-                self.graph_dict.iteritems() for node, weight in edge_dict.items()]
+                self.graph_dict.iteritems()
+                for node, weight in edge_dict.iteritems()]
 
     def add_node(self, node):
         """add a new node 'n' to the graph"""