app.py

import matplotlib.pyplot as plt
import networkx as nx
import json

class Graph:
    def __init__(self):
        self.nodes = set()
        self.edges = {}

    def add_node(self, name):
        self.nodes.add(name)
        if name not in self.edges:
            self.edges[name] = {}

    def add_edge(self, node1, node2, edge_name=""):
        self.add_node(node1)
        self.add_node(node2)
        self.edges[node1][node2] = edge_name
        self.edges[node2][node1] = edge_name

    def color_graph(self):
        color_assignment = {}
        for node in sorted(self.nodes):
            neighbor_colors = {color_assignment.get(neigh) for neigh in self.edges[node] if neigh in color_assignment}
            color = 0
            while color in neighbor_colors:
                color += 1
            color_assignment[node] = color
        num_colors = max(color_assignment.values()) + 1 if color_assignment else 0
        return color_assignment, num_colors

    def visualize(self, coloring=None):
        G = nx.Graph()
        for node in self.nodes:
            G.add_node(node)
        for node, neighbors in self.edges.items():
            for neighbor, edge_name in neighbors.items():
                if (neighbor, node) not in G.edges:
                    G.add_edge(node, neighbor, label=edge_name)
        pos = nx.spring_layout(G)
        if coloring:
            colors = [coloring[node] for node in G.nodes()]
        else:
            colors = "lightblue"
        nx.draw(G, pos, with_labels=True, node_color=colors, cmap=plt.cm.Set3, node_size=800)
        edge_labels = nx.get_edge_attributes(G, 'label')
        nx.draw_networkx_edge_labels(G, pos, edge_labels=edge_labels, font_color='red')
        plt.show()

def load_graph_from_json(filepath):
    with open(filepath, "r") as f:
        data = json.load(f)
    g = Graph()
    for node in data.get("nodes", []):
        g.add_node(node)
    for edge in data.get("edges", []):
        node1 = edge["from"]
        node2 = edge["to"]
        name = edge.get("name", "")
        g.add_edge(node1, node2, name)
    return g

if __name__ == "__main__":
    g = load_graph_from_json("graph.json")
    coloring, num_colors = g.color_graph()
    print("Coloring:", coloring)
    print("Number of colors used:", num_colors)
    g.visualize(coloring)