diff env/lib/python3.9/site-packages/networkx/algorithms/tests/test_planar_drawing.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/networkx/algorithms/tests/test_planar_drawing.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,272 @@
+import pytest
+import networkx as nx
+from networkx.algorithms.planar_drawing import triangulate_embedding
+import math
+
+
+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
+                    ) / float(determinant)
+                    py = (x1 * y2 - y1 * x2) * (y3 - y4) - (y1 - y2) * (
+                        x3 * y4 - y3 * x4
+                    ) / float(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 not 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