graph.py

class Graph():
    def __init__(self, size):
        self.adj = [ [0] * size for i in range(size)]
        self.size = size

    def add_edge(self, orig, dest):
        if orig > self.size or dest > self.size or orig < 0 or dest < 0:
            print("Invalid Edge")
        else:
            self.adj[orig-1][dest-1] = 1
            self.adj[dest-1][orig-1] = 1

    def remove_edge(self, orig, dest):
        if orig > self.size or dest > self.size or orig < 0 or dest < 0:
            print("Invalid Edge")
        else:
            self.adj[orig-1][dest-1] = 0
            self.adj[dest-1][orig-1] = 0

    def display(self):
        for row in self.adj:
            print()
            for val in row:
                print('{:4}'.format(val),end="")

#a sample Graph
G = Graph(4)
G.add_edge(1, 3)
G.add_edge(3, 4)
G.add_edge(2, 4)
G.display()