def test_color_with_degree_four_node():
G = igraph.Graph.Full(n=6)
G.delete_edges([(0, 1)])
assert_that(G.degree(0)).is_equal_to(4)
planar_five_color(G)
assert_that(properly_colored(G)).is_true()
def test_color_five_regular_planar_graph():
G = igraph.Graph(n=12)
flower = [(0, 1), (0, 2), (0, 3), (0, 4), (0, 5),
(1, 2), (1, 5), (1, 6), (1, 7),
(2, 3), (2, 7), (2, 8),
(3, 4), (3, 8), (3, 9),
(4, 5), (4, 9), (4, 10),
(5, 6), (5, 10),
(6, 7), (6, 10), (6, 11),
(7, 8), (7, 11),
(8, 9), (8, 11),
(9, 10), (9, 11),
(10, 11)]
G.add_edges(flower)
planar_five_color(G)
assert_that(properly_colored(G)).is_true()
import igraph
from igraph.drawing import plot
from color import planar_five_color
color_dict = {0: 'green', 1: 'blue', 2: 'red', 3: 'yellow', 4: 'pink'}
five_regular = igraph.Graph(n=12)
five_reg = [(0, 1), (0, 2), (0, 3), (0, 4), (0, 5), (1, 2), (1, 5), (1, 6),
(1, 7), (2, 3), (2, 7), (2, 8), (3, 4), (3, 8), (3, 9), (4, 5),
(4, 9), (4, 10), (5, 6), (5, 10), (6, 7), (6, 10), (6, 11), (7, 8),
(7, 11), (8, 9), (8, 11), (9, 10), (9, 11), (10, 11)]
five_regular.add_edges(five_reg)
graph_colored = planar_five_color(five_regular)
graph_colored.vs['color'] = [
color_dict[color] for color in graph_colored.vs['color']
]
layout = graph_colored.layout("kk")
plot(graph_colored, target='graph.png', layout=layout)
def test_failure_of_recursive_call():
G = igraph.Graph.Full(n=7)
G.delete_edges([(0, 1)]) # leaves node 0 with deg 5
with pytest.raises(NotPlanarError):
planar_five_color(G)
def test_failure_of_deg_5_node():
G = igraph.Graph.Full(n=7)
with pytest.raises(ValueError):
planar_five_color(G)
def test_three_node_empty_graph():
G = igraph.Graph(n=3)
planar_five_color(G)
assert_that(G.vs['color']).is_equal_to([0, 1, 2])