Data commit

Task/Faces-from-a-mesh/Python/faces-from-a-mesh.py

@@ -0,0 +1,50 @@
+def perim_equal(p1, p2):
+    # Cheap tests first
+    if len(p1) != len(p2) or set(p1) != set(p2):
+        return False
+    if any(p2 == (p1[n:] + p1[:n]) for n in range(len(p1))):
+        return True
+    p2 = p2[::-1] # not inplace
+    return any(p2 == (p1[n:] + p1[:n]) for n in range(len(p1)))
+
+def edge_to_periphery(e):
+    edges = sorted(e)
+    p = list(edges.pop(0)) if edges else []
+    last = p[-1] if p else None
+    while edges:
+        for n, (i, j) in enumerate(edges):
+            if i == last:
+                p.append(j)
+                last = j
+                edges.pop(n)
+                break
+            elif j == last:
+                p.append(i)
+                last = i
+                edges.pop(n)
+                break
+        else:
+            #raise ValueError(f'Invalid edge format: {e}')
+            return ">>>Error! Invalid edge format<<<"
+    return p[:-1]
+
+if __name__ == '__main__':
+    print('Perimeter format equality checks:')
+    for eq_check in [
+            { 'Q': (8, 1, 3),
+              'R': (1, 3, 8)},
+            { 'U': (18, 8, 14, 10, 12, 17, 19),
+              'V': (8, 14, 10, 12, 17, 19, 18)} ]:
+        (n1, p1), (n2, p2) = eq_check.items()
+        eq = '==' if perim_equal(p1, p2) else '!='
+        print(' ', n1, eq, n2)
+
+    print('\nEdge to perimeter format translations:')
+    edge_d = {
+     'E': {(1, 11), (7, 11), (1, 7)},
+     'F': {(11, 23), (1, 17), (17, 23), (1, 11)},
+     'G': {(8, 14), (17, 19), (10, 12), (10, 14), (12, 17), (8, 18), (18, 19)},
+     'H': {(1, 3), (9, 11), (3, 11), (1, 11)}
+            }
+    for name, edges in edge_d.items():
+        print(f"  {name}: {edges}\n     -> {edge_to_periphery(edges)}")