# Graphs and Graph Search

Learn about and implement graphs and graph search in Python.

Start## Key Concepts

Review core concepts you need to learn to master this subject

Implementing a Graph Class

Implementing a Graph Class

```
class Vertex:
"""Key methods of Vertex class"""
def __init__(self, value):
def add_edge(self, vertex, weight = 0):
def get_edges(self):
class Graph:
"""Key methods of Graph class"""
def __init__(self, directed = False):
def add_vertex(self, vertex):
def add_edge(self, from_vertex, to_vertex, weight = 0):
def find_path(self, start_vertex, end_vertex):
```

The basis of a `Graph`

class in Python is the implementation of two classes, `Graph`

and `Vertex`

, which establish the essential functionality to create a variety of graphs.

The `Vertex`

class allows for storage of connecting vertices with a dictionary and adjustment of their edges as well.

The `Graph`

class builds upon the `Vertex`

methods and allows addition of vertices and edges, setting the directionality of edges, and determining if a path exists between two vertices.

Graphs: Conceptual

Lesson 1 of 4

- 1Graphs are the perfect data structure for modeling networks, which make them an indispensable piece of your data structure toolkit. They’re composed of nodes, or
*vertices*, which hold data, and _… - 2Graphs have varying degrees of connection. The higher the ratio of edges to vertices, the more connected the graph. This graph represents a social network; people are vertices and edges are friend…
- 3We’re building a graph of favorite neighborhood destinations (vertices) and routes (edges), but not all edges are equal. It takes longer to travel between Gym and Museum than it does to travel bet…
- 4Imagine you’re a superhero escaping a villain’s lair. As you move from perilous room to perilous room, the doors close immediately behind you, barring any return. For this dramatic example, we n…
- 5We typically represent the vertex-edge relationship of a graph in two ways: an adjacency list or an adjacency matrix. An adjacency matrix is a table. Across the top, every vertex in the graph ap…
- 6Graphs are an essential data structure in computer science for modeling networks. Let’s review some key terms: * vertex: A node in a graph. * edge: A connection between two vertices. * adjacent: W…

## What you'll create

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## How you'll master it

Stress-test your knowledge with quizzes that help commit syntax to memory