Add radius balance algorithm

networks/polylines.py

@@ -0,0 +1,64 @@
+from math import sqrt
+import numpy as np
+
+
+class Point2D:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+    def __repr__(self):
+        return f"({self.x} {self.y})"
+
+    def copy(self):
+        return Point2D(self.x, self.y)
+
+    def get_coordinates(self):
+        return (self.x, self.y)
+
+
+def radius_balance(polylines, i):
+    """
+    Returns the radius that balances the radii on either end segement i.
+    """
+
+    vectors = [None] * 3
+    lengths = [None] * 3
+    unit_vectors = [None] * 3
+    tangente = [None] * 3
+
+    for j in range(3):
+        vectors[j] = polylines[i+j] - polylines[i+j-1]
+        lengths[j] = np.linalg.norm(vectors[j])
+        unit_vectors[j] = vectors[j]/lengths[j]
+
+    print("\n\n", vectors, "\n\n", lengths, "\n\n", unit_vectors, "\n\n")
+
+    for k in range(2):
+        cross = np.dot(unit_vectors[k+1], unit_vectors[k])
+        print(cross)
+        tangente[k] = sqrt((1+cross)/(1-cross))
+        print("\n", tangente[k])
+
+    alpha_a = min(lengths[0], (lengths[1]*tangente[1]) /
+                  (tangente[0] + tangente[1]))
+    alpha_b = min(lengths[2], lengths[1]-alpha_a)
+
+    return alpha_a, alpha_b, max(tangente[0]*alpha_a, tangente[1]*alpha_b)
+
+
+def coordinates_to_vectors(coordinates):
+    vectors = []
+    for coordinate in coordinates:
+        vectors.append(np.array(coordinate.get_coordinates()))
+
+    if (len(vectors) == 1):
+        return vectors[0]
+    else:
+        return vectors
+
+
+polyline = coordinates_to_vectors(
+    (Point2D(0, 0), Point2D(0, 10), Point2D(10, 10), Point2D(10, 20)))
+
+print(radius_balance(polyline, 1))