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Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_planar_drawing.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_planar_drawing.py | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_planar_drawing.py b/.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_planar_drawing.py new file mode 100644 index 00000000..a5de0e03 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_planar_drawing.py @@ -0,0 +1,274 @@ +import math + +import pytest + +import networkx as nx +from networkx.algorithms.planar_drawing import triangulate_embedding + + +def test_graph1(): + embedding_data = {0: [1, 2, 3], 1: [2, 0], 2: [3, 0, 1], 3: [2, 0]} + check_embedding_data(embedding_data) + + +def test_graph2(): + embedding_data = { + 0: [8, 6], + 1: [2, 6, 9], + 2: [8, 1, 7, 9, 6, 4], + 3: [9], + 4: [2], + 5: [6, 8], + 6: [9, 1, 0, 5, 2], + 7: [9, 2], + 8: [0, 2, 5], + 9: [1, 6, 2, 7, 3], + } + check_embedding_data(embedding_data) + + +def test_circle_graph(): + embedding_data = { + 0: [1, 9], + 1: [0, 2], + 2: [1, 3], + 3: [2, 4], + 4: [3, 5], + 5: [4, 6], + 6: [5, 7], + 7: [6, 8], + 8: [7, 9], + 9: [8, 0], + } + check_embedding_data(embedding_data) + + +def test_grid_graph(): + embedding_data = { + (0, 1): [(0, 0), (1, 1), (0, 2)], + (1, 2): [(1, 1), (2, 2), (0, 2)], + (0, 0): [(0, 1), (1, 0)], + (2, 1): [(2, 0), (2, 2), (1, 1)], + (1, 1): [(2, 1), (1, 2), (0, 1), (1, 0)], + (2, 0): [(1, 0), (2, 1)], + (2, 2): [(1, 2), (2, 1)], + (1, 0): [(0, 0), (2, 0), (1, 1)], + (0, 2): [(1, 2), (0, 1)], + } + check_embedding_data(embedding_data) + + +def test_one_node_graph(): + embedding_data = {0: []} + check_embedding_data(embedding_data) + + +def test_two_node_graph(): + embedding_data = {0: [1], 1: [0]} + check_embedding_data(embedding_data) + + +def test_three_node_graph(): + embedding_data = {0: [1, 2], 1: [0, 2], 2: [0, 1]} + check_embedding_data(embedding_data) + + +def test_multiple_component_graph1(): + embedding_data = {0: [], 1: []} + check_embedding_data(embedding_data) + + +def test_multiple_component_graph2(): + embedding_data = {0: [1, 2], 1: [0, 2], 2: [0, 1], 3: [4, 5], 4: [3, 5], 5: [3, 4]} + check_embedding_data(embedding_data) + + +def test_invalid_half_edge(): + with pytest.raises(nx.NetworkXException): + embedding_data = {1: [2, 3, 4], 2: [1, 3, 4], 3: [1, 2, 4], 4: [1, 2, 3]} + embedding = nx.PlanarEmbedding() + embedding.set_data(embedding_data) + nx.combinatorial_embedding_to_pos(embedding) + + +def test_triangulate_embedding1(): + embedding = nx.PlanarEmbedding() + embedding.add_node(1) + expected_embedding = {1: []} + check_triangulation(embedding, expected_embedding) + + +def test_triangulate_embedding2(): + embedding = nx.PlanarEmbedding() + embedding.connect_components(1, 2) + expected_embedding = {1: [2], 2: [1]} + check_triangulation(embedding, expected_embedding) + + +def check_triangulation(embedding, expected_embedding): + res_embedding, _ = triangulate_embedding(embedding, True) + assert ( + res_embedding.get_data() == expected_embedding + ), "Expected embedding incorrect" + res_embedding, _ = triangulate_embedding(embedding, False) + assert ( + res_embedding.get_data() == expected_embedding + ), "Expected embedding incorrect" + + +def check_embedding_data(embedding_data): + """Checks that the planar embedding of the input is correct""" + embedding = nx.PlanarEmbedding() + embedding.set_data(embedding_data) + pos_fully = nx.combinatorial_embedding_to_pos(embedding, False) + msg = "Planar drawing does not conform to the embedding (fully triangulation)" + assert planar_drawing_conforms_to_embedding(embedding, pos_fully), msg + check_edge_intersections(embedding, pos_fully) + pos_internally = nx.combinatorial_embedding_to_pos(embedding, True) + msg = "Planar drawing does not conform to the embedding (internal triangulation)" + assert planar_drawing_conforms_to_embedding(embedding, pos_internally), msg + check_edge_intersections(embedding, pos_internally) + + +def is_close(a, b, rel_tol=1e-09, abs_tol=0.0): + # Check if float numbers are basically equal, for python >=3.5 there is + # function for that in the standard library + return abs(a - b) <= max(rel_tol * max(abs(a), abs(b)), abs_tol) + + +def point_in_between(a, b, p): + # checks if p is on the line between a and b + x1, y1 = a + x2, y2 = b + px, py = p + dist_1_2 = math.sqrt((x1 - x2) ** 2 + (y1 - y2) ** 2) + dist_1_p = math.sqrt((x1 - px) ** 2 + (y1 - py) ** 2) + dist_2_p = math.sqrt((x2 - px) ** 2 + (y2 - py) ** 2) + return is_close(dist_1_p + dist_2_p, dist_1_2) + + +def check_edge_intersections(G, pos): + """Check all edges in G for intersections. + + Raises an exception if an intersection is found. + + Parameters + ---------- + G : NetworkX graph + pos : dict + Maps every node to a tuple (x, y) representing its position + + """ + for a, b in G.edges(): + for c, d in G.edges(): + # Check if end points are different + if a != c and b != d and b != c and a != d: + x1, y1 = pos[a] + x2, y2 = pos[b] + x3, y3 = pos[c] + x4, y4 = pos[d] + determinant = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4) + if determinant != 0: # the lines are not parallel + # calculate intersection point, see: + # https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection + px = (x1 * y2 - y1 * x2) * (x3 - x4) - (x1 - x2) * ( + x3 * y4 - y3 * x4 + ) / determinant + py = (x1 * y2 - y1 * x2) * (y3 - y4) - (y1 - y2) * ( + x3 * y4 - y3 * x4 + ) / determinant + + # Check if intersection lies between the points + if point_in_between(pos[a], pos[b], (px, py)) and point_in_between( + pos[c], pos[d], (px, py) + ): + msg = f"There is an intersection at {px},{py}" + raise nx.NetworkXException(msg) + + # Check overlap + msg = "A node lies on a edge connecting two other nodes" + if ( + point_in_between(pos[a], pos[b], pos[c]) + or point_in_between(pos[a], pos[b], pos[d]) + or point_in_between(pos[c], pos[d], pos[a]) + or point_in_between(pos[c], pos[d], pos[b]) + ): + raise nx.NetworkXException(msg) + # No edge intersection found + + +class Vector: + """Compare vectors by their angle without loss of precision + + All vectors in direction [0, 1] are the smallest. + The vectors grow in clockwise direction. + """ + + __slots__ = ["x", "y", "node", "quadrant"] + + def __init__(self, x, y, node): + self.x = x + self.y = y + self.node = node + if self.x >= 0 and self.y > 0: + self.quadrant = 1 + elif self.x > 0 and self.y <= 0: + self.quadrant = 2 + elif self.x <= 0 and self.y < 0: + self.quadrant = 3 + else: + self.quadrant = 4 + + def __eq__(self, other): + return self.quadrant == other.quadrant and self.x * other.y == self.y * other.x + + def __lt__(self, other): + if self.quadrant < other.quadrant: + return True + elif self.quadrant > other.quadrant: + return False + else: + return self.x * other.y < self.y * other.x + + def __ne__(self, other): + return self != other + + def __le__(self, other): + return not other < self + + def __gt__(self, other): + return other < self + + def __ge__(self, other): + return not self < other + + +def planar_drawing_conforms_to_embedding(embedding, pos): + """Checks if pos conforms to the planar embedding + + Returns true iff the neighbors are actually oriented in the orientation + specified of the embedding + """ + for v in embedding: + nbr_vectors = [] + v_pos = pos[v] + for nbr in embedding[v]: + new_vector = Vector(pos[nbr][0] - v_pos[0], pos[nbr][1] - v_pos[1], nbr) + nbr_vectors.append(new_vector) + # Sort neighbors according to their phi angle + nbr_vectors.sort() + for idx, nbr_vector in enumerate(nbr_vectors): + cw_vector = nbr_vectors[(idx + 1) % len(nbr_vectors)] + ccw_vector = nbr_vectors[idx - 1] + if ( + embedding[v][nbr_vector.node]["cw"] != cw_vector.node + or embedding[v][nbr_vector.node]["ccw"] != ccw_vector.node + ): + return False + if cw_vector.node != nbr_vector.node and cw_vector == nbr_vector: + # Lines overlap + return False + if ccw_vector.node != nbr_vector.node and ccw_vector == nbr_vector: + # Lines overlap + return False + return True |