mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-11-27 23:11:09 +00:00
61eedc16c3
* refactor: Fix matrix display deprecation * refactor: Remove useless `print` and `pass` statements * revert: Replace broken doctests * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * revert: Fix failing doctests * chore: Satisfy pre-commit Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
68 lines
2.1 KiB
Python
68 lines
2.1 KiB
Python
"""
|
|
* Author: Manuel Di Lullo (https://github.com/manueldilullo)
|
|
* Description: Random graphs generator.
|
|
Uses graphs represented with an adjacency list.
|
|
|
|
URL: https://en.wikipedia.org/wiki/Random_graph
|
|
"""
|
|
|
|
import random
|
|
|
|
|
|
def random_graph(
|
|
vertices_number: int, probability: float, directed: bool = False
|
|
) -> dict:
|
|
"""
|
|
Generate a random graph
|
|
@input: vertices_number (number of vertices),
|
|
probability (probability that a generic edge (u,v) exists),
|
|
directed (if True: graph will be a directed graph,
|
|
otherwise it will be an undirected graph)
|
|
@examples:
|
|
>>> random.seed(1)
|
|
>>> random_graph(4, 0.5)
|
|
{0: [1], 1: [0, 2, 3], 2: [1, 3], 3: [1, 2]}
|
|
>>> random.seed(1)
|
|
>>> random_graph(4, 0.5, True)
|
|
{0: [1], 1: [2, 3], 2: [3], 3: []}
|
|
"""
|
|
graph: dict = {i: [] for i in range(vertices_number)}
|
|
|
|
# if probability is greater or equal than 1, then generate a complete graph
|
|
if probability >= 1:
|
|
return complete_graph(vertices_number)
|
|
# if probability is lower or equal than 0, then return a graph without edges
|
|
if probability <= 0:
|
|
return graph
|
|
|
|
# for each couple of nodes, add an edge from u to v
|
|
# if the number randomly generated is greater than probability probability
|
|
for i in range(vertices_number):
|
|
for j in range(i + 1, vertices_number):
|
|
if random.random() < probability:
|
|
graph[i].append(j)
|
|
if not directed:
|
|
# if the graph is undirected, add an edge in from j to i, either
|
|
graph[j].append(i)
|
|
return graph
|
|
|
|
|
|
def complete_graph(vertices_number: int) -> dict:
|
|
"""
|
|
Generate a complete graph with vertices_number vertices.
|
|
@input: vertices_number (number of vertices),
|
|
directed (False if the graph is undirected, True otherwise)
|
|
@example:
|
|
>>> complete_graph(3)
|
|
{0: [1, 2], 1: [0, 2], 2: [0, 1]}
|
|
"""
|
|
return {
|
|
i: [j for j in range(vertices_number) if i != j] for i in range(vertices_number)
|
|
}
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|