In this assignment, you will work with graphs. Begin with the "useGraph.py" starter file. This file contains comment instructions that tell you where to add your code to do various tasks that use and manipulate graphs. Make sure you read the "Programming Activity 8 - Guidance" document. Make sure your output matches the "Programming Activity 8 - Expected Output" document. """ File: useGraph.py Author: Derrf Seitz This program exercises graphs. The following files must be in the same folder: abstractcollection.py graph.py """ # # Replace with your name. # Replace any "" comments with your own code statement(s) # to accomplish the specified task. # DO NOT CHANGE ANY OTHER CODE. from graph import LinkedDirectedGraph # Part 1: # Complete the following function: def topologicalSort(graph): <your code> # graph = LinkedDirectedGraph() # The graph represents the following course prerequisites: # A requires nothing # B requires nothing # C requires A # D requires A, B, and C # E requires C # F requires B and D # G requires E and F # H requires C, F, and G # Part 2: # Add the vertices: <your code> # Part 3: # Add the edges: <your code> # print("Graph:") print(graph) print() print("Courses:") # Part 4: # Display each vertex on a separate line: <your code> # print() print("Prerequisites:") # Part 5: # Display each edge on a separate line: <your code> # print() print("One possible order to take the courses:") # Part 6: # Display the courses in prerequisite (topological) order: <your code> # print() """ File: graph.py Author: Ken Lambert, copyright 2015, 2020 Used by permission. Adds the in, +, ==, and clone operations to support graph-specific behavior. """ from abstractcollection import AbstractCollection class LinkedEdge(object): # An edge has a source vertex, a destination vertex, # a weight, and a mark attribute. # Constructor def __init__(self, fromVertex, toVertex, weight = None): self.vertex1 = fromVertex self.vertex2 = toVertex self.weight = weight self.mark = False # Accessor methods def __eq__(self, other): """Two edges are equal if they connect the same vertices.""" if self is other: return True if type(self) != type(other): return False return self.vertex1 == other.vertex1 and \ self.vertex2 == other.vertex2 def __hash__(self): # Derrf Seitz 11/16/2020 """Hash method for an edge.""" return hash(self.vertex1.label + self.vertex2.label) def __str__(self): """Returns the string representation of the edge.""" return str(self.vertex1) + ">" + \ str(self.vertex2) + ":" + \ str(self.weight) def getFromVertex(self): # Derrf Seitz 12/17/2015 """Returns the edge's origin vertex.""" return self.vertex1 def getOtherVertex(self, thisVertex): """Returns the vertex opposite thisVertex.""" if thisVertex == None or thisVertex == self.vertex2: return self.vertex1 else: return self.vertex2 def getToVertex(self): """Returns the edge's destination vertex.""" return self.vertex2 def getWeight(self): """Returns the edge's weight.""" return self.weight def isMarked(s.

1. In this assignment, you will work with graphs. Begin with the "useGraph.py" starter file. This
file contains comment instructions that tell you where to add your code to do various tasks that
use and manipulate graphs. Make sure you read the "Programming Activity 8 - Guidance"
document. Make sure your output matches the "Programming Activity 8 - Expected Output"
document.
""" File: useGraph.py
Author: Derrf Seitz
This program exercises graphs.
The following files must be in the same folder:
abstractcollection.py
graph.py
"""
# # Replace with your name.
# Replace any "" comments with your own code statement(s)
# to accomplish the specified task.
# DO NOT CHANGE ANY OTHER CODE. from graph import LinkedDirectedGraph
# Part 1:
# Complete the following function: def topologicalSort(graph):
<your code>
# graph = LinkedDirectedGraph()
# The graph represents the following course prerequisites:
# A requires nothing
# B requires nothing
# C requires A
# D requires A, B, and C

2. # E requires C
# F requires B and D
# G requires E and F
# H requires C, F, and G
# Part 2:
# Add the vertices:
<your code>
# Part 3:
# Add the edges:
<your code>
# print("Graph:") print(graph) print() print("Courses:")
# Part 4:
# Display each vertex on a separate line:
<your code>
# print()
print("Prerequisites:")
# Part 5:
# Display each edge on a separate line:
<your code>
# print()
print("One possible order to take the courses:")
# Part 6:
# Display the courses in prerequisite (topological) order:

3. <your code>
# print()
"""
File: graph.py
Author: Ken Lambert, copyright 2015, 2020
Used by permission.
Adds the in, +, ==, and clone operations to support graph-specific behavior.
"""
from abstractcollection import AbstractCollection
class LinkedEdge(object):
# An edge has a source vertex, a destination vertex,
# a weight, and a mark attribute.
# Constructor
def __init__(self, fromVertex, toVertex, weight = None):
self.vertex1 = fromVertex
self.vertex2 = toVertex
self.weight = weight
self.mark = False
# Accessor methods
def __eq__(self, other):
"""Two edges are equal if they connect
the same vertices."""
if self is other:
return True
if type(self) != type(other):
return False
return self.vertex1 == other.vertex1 and
self.vertex2 == other.vertex2
def __hash__(self): # Derrf Seitz 11/16/2020
"""Hash method for an edge."""
return hash(self.vertex1.label + self.vertex2.label)
def __str__(self):
"""Returns the string representation of the edge."""
return str(self.vertex1) + ">" +
str(self.vertex2) + ":" +
str(self.weight)

4. def getFromVertex(self): # Derrf Seitz 12/17/2015
"""Returns the edge's origin vertex."""
return self.vertex1
def getOtherVertex(self, thisVertex):
"""Returns the vertex opposite thisVertex."""
if thisVertex == None or thisVertex == self.vertex2:
return self.vertex1
else:
return self.vertex2
def getToVertex(self):
"""Returns the edge's destination vertex."""
return self.vertex2
def getWeight(self):
"""Returns the edge's weight."""
return self.weight
def isMarked(self):
"""Returns True if the edge is marked
or False otherwise."""
return self.mark
# Mutator methods
def clearMark(self):
"""Clears the mark on the edge."""
self.mark = False
def setMark(self):
"""Sets the mark on the edge."""
self.mark = True
def setWeight(self, weight):
"""Sets the weight on the edge to weight."""
self.weight = weight
class LinkedVertex(object):
# A vertex has a label, a list of incident edges,
# and a mark attribute.
# Constructor
def __init__(self, label):
self.label = label

5. self.edgeList = list()
self.mark = False
# Accessor methods
def __eq__(self, other):
"""Two vertices are equal if they have
the same labels."""
if self is other:
return True
if type(self) != type(other):
return False
return self.getLabel() == other.getLabel()
def __hash__(self): # Derrf Seitz 12/16/2015
"""Hash method for a vertex."""
return hash(self.label)
def __str__(self):
"""Returns the string representation of the vertex."""
return str(self.label)
def getEdgeTo(self, toVertex):
"""Returns the connecting edge if it exists, or
None otherwise."""
edge = LinkedEdge(self, toVertex)
try:
return self.edgeList[self.edgeList.index(edge)]
except:
return None
def getLabel(self):
"""Returns the label of the vertex."""
return self.label
def incidentEdges(self):
"""Returns the incident edges of this vertex."""
return iter(self.edgeList)
def isMarked(self):
"""Returns True if the vertex is marked
or False otherwise."""
return self.mark
def neighboringVertices(self):
"""Returns the neighboring vertices of this vertex."""
vertices = list()

6. for edge in self.edgeList:
vertices.append(edge.getOtherVertex(self))
return iter(vertices)
# Mutator methods
def addEdgeTo(self, toVertex, weight):
"""Connects the vertices with an edge."""
edge = LinkedEdge(self, toVertex, weight)
self.edgeList.append(edge)
def clearMark(self):
"""Clears the mark on the vertex."""
self.mark = False;
def removeEdgeTo(self, toVertex):
"""Returns True if the edge exists and is removed,
or False otherwise."""
edge = LinkedEdge(self, toVertex)
if edge in self.edgeList:
self.edgeList.remove(edge)
return True
else:
return False
def setLabel(self, label, g):
"""Sets the vertex's label to label."""
g.vertices.pop(self.label, None)
g.vertices[label] = self
self.label = label
def setMark(self):
"""Sets the mark on the vertex."""
self.mark = True
class LinkedDirectedGraph(AbstractCollection):
# A graph has a count of vertices, a count of edges,
# and a dictionary of label/vertex pairs.
# Class variables
INTERFACE = "GraphInterface"
# Constructor
def __init__(self, sourceCollection = None):
self.edgeCount = 0
self.vertices = dict() # Dictionary of vertices

7. AbstractCollection.__init__(self, sourceCollection)
# Accessor methods
def __contains__(self, item):
"""Returns True if item is a label in a vertex,
or False otherwise."""
for vertex in self:
if vertex.getLabel() == item:
return True
return False
def __eq__(self, other):
"""Returns True if self and other are identical, or
True if self and other are of the same type, have the
same number of vertices, and these vertices are connected
in the same manner (including same labels and edge weights)."""
# Check simple criteria first
if self is other:
return True
if type(self) != type(other):
return False
if len(self) != len(other):
return False
for vertex in self:
# All vertex labels must match
if not vertex.getLabel() in other:
print("Mismatched vertices")
return False
# Vertices with the same labels must have the same
# incident edges
otherVertex = other.getVertex(vertex.getLabel())
selfEdges = list(vertex.incidentEdges())
otherEdges = list(otherVertex.incidentEdges())
if len(selfEdges) != len(otherEdges):
return False
for edge in selfEdges:
found = False
for otherEdge in otherEdges:
if edge == otherEdge and
edge.getWeight() == otherEdge.getWeight():
found = True
break
if not found: return False
return True
def __iter__(self):

8. """Supports iteration over a view of self (the vertices)."""
return self.getVertices()
def __str__(self):
"""Returns the string representation of the graph."""
result = str(len(self)) + " Vertices: "
for vertex in self.vertices:
result += " " + str(vertex)
result += "n";
result += str(self.sizeEdges()) + " Edges: "
for edge in self.edges():
result += " " + str(edge)
return result
def containsEdge(self, fromLabel, toLabel):
"""Returns True if an edge connects the vertices,
or False otherwise."""
return self.getEdge(fromLabel, toLabel) != None
def containsVertex (self, label):
return label in self.vertices
def clone(self):
"""Returns an exact copy of self, including vertex labels,
edges connecting vertices, and edge weights."""
newGraph = type(self)(map(lambda vertex: vertex.getLabel(), self))
for vertex in self:
for neighbor in vertex.neighboringVertices():
edge = vertex.getEdgeTo(neighbor)
newGraph.addEdge(vertex.getLabel(),
neighbor.getLabel(),
edge.getWeight())
return newGraph
def edges(self):
"""Supports iteration over the edges in the graph."""
result = set()
for vertex in self.getVertices():
edges = vertex.incidentEdges()
result = result.union(set(edges))
return iter(result)
def getEdge(self, fromLabel, toLabel):
"""Returns the edge connecting the two vertices, or None if
no edge exists.
Precondition: vertices with fromLabel and toLabel must

9. already be in the graph.
Raises: AttibuteError if the vertices
are not already in the graph."""
fromVertex = self.getVertex(fromLabel)
toVertex = self.getVertex(toLabel)
return fromVertex.getEdgeTo(toVertex)
def getVertex(self, label):
"""Precondition: a vertex with label must already be in the graph.
Raises: AttibuteError if a vertex with label is not already in the graph."""
if not self.containsVertex(label):
raise AttributeError("Label " + str(label) + " not in graph.""")
return self.vertices[label]
def getVertices(self):
"""Supports iteration over the vertices in the graph."""
return iter(self.vertices.values())
def incidentEdges(self, label):
"""Supports iteration over the incident edges of the
given verrtex.
Precondition: a vertex with label must already be in the graph.
Raises: AttibuteError if a vertex with label is not already in the graph."""
return self.getVertex(label).incidentEdges()
def neighboringVertices(self, label):
"""Supports iteration over the neighboring vertices of the
given verrtex.
Precondition: a vertex with label must already be in the graph.
Raises: AttibuteError if a vertex with label is not already in the graph."""
return self.getVertex(label).neighboringVertices()
def sizeEdges(self):
"""Returns the number of edges."""
return self.edgeCount
def sizeVertices(self):
"""Returns the number of vertices."""
return len(self)
# Mutator methods
def __add__(self, other):
"""Returns a new collection consisting of the
items in self and other. This will be a graph with
the contents of the operand graphs as separate components.
Precondition: the labels in the two graph operands are disjoint.

10. Raises: AttributeError if the labels in the two operand graphs
are not disjoint."""
newGraph = self.clone()
for vertex in other:
newGraph.add(vertex.getLabel())
for vertex in other:
for neighbor in vertex.neighboringVertices():
edge = vertex.getEdgeTo(neighbor)
newGraph.addEdge(vertex.getLabel(),
neighbor.getLabel(),
edge.getWeight())
return newGraph
def add(self, label):
"""For compatibility with other collections."""
self.addVertex(label)
def addEdge(self, fromLabel, toLabel, weight):
"""Connects the vertices with an edge with the given weight.
Preconditions: vertices with fromLabel and toLabel must
already be in the graph.
The vertices must not already be connected by an edge.
Raises: AttibuteError if the vertices
are not already in the graph or they are already connected."""
fromVertex = self.getVertex(fromLabel)
toVertex = self.getVertex(toLabel)
if self.getEdge(fromLabel, toLabel):
raise AttributeError("An edge already connects " +
str(fromLabel) + " and " +
str(toLabel))
fromVertex.addEdgeTo(toVertex, weight)
self.edgeCount += 1
def addVertex(self, label):
"""Precondition: a vertex with label must not
already be in the graph.
Raises: AttibuteError if a vertex with label
is already in the graph."""
if self.containsVertex(label):
raise AttributeError("Label " + str(label) + " already in graph.""")
self.vertices[label] = LinkedVertex(label)
self.size += 1
def clear(self):
"""Clears the graph."""
self.size = 0

11. self.edgeCount = 0
self.vertices = dict()
def clearEdgeMarks(self):
"""Clears all the edge marks."""
for edge in self.edges():
edge.clearMark()
def clearVertexMarks(self):
"""Clears all the vertex marks."""
for vertex in self.getVertices():
vertex.clearMark()
def removeEdge (self, fromLabel, toLabel):
"""Returns True if the edge was removed, or False otherwise.
Precondition: vertices with fromLabel and toLabel must
already be in the graph.
Raises: AttibuteError if the vertices
are not already in the graph."""
fromVertex = self.getVertex(fromLabel)
toVertex = self.getVertex(toLabel)
edgeRemovedFlg = fromVertex.removeEdgeTo(toVertex)
if edgeRemovedFlg:
self.edgeCount -= 1
return edgeRemovedFlg
def removeVertex(self, label):
"""Returns True if the vertex was removed, or False otherwise."""
removedVertex = self.vertices.pop(label, None)
if removedVertex is None:
return False
# Examine all other vertices to remove edges
# directed at the removed vertex
for vertex in self.getVertices():
if vertex.removeEdgeTo(removedVertex):
self.edgeCount -= 1
# Examine all edges from the removed vertex to others
for edge in removedVertex.incidentEdges():
self.edgeCount -= 1
self.size -= 1
return True