backend/src/optimizer.py

@@ -40,9 +40,6 @@ def untangle2(resx: list) :
 
     return order
 
-
-
-
 # Convert the result (edges from j to k like d_25 = edge between vertex 2 and vertex 5) into the list of indices corresponding to the landmarks
 def untangle(resx: list) :
     N = len(resx)                # length of res
@@ -102,7 +99,49 @@ def print_res(res: list, landmarks: list, P) :
     steps = path_length(P, abs(res.x))
     print("\nSteps walked : " + str(steps))
 
-# Constraint to not have d14 and d41 simultaneously
+
+# Checks for cases of circular symmetry in the result
+def has_circle(resx: list) :
+    N = len(resx)                   # length of res
+    L = int(np.sqrt(N))             # number of landmarks. CAST INTO INT but should not be a problem because N = L**2 by def.
+    n_edges = resx.sum()      # number of edges
+
+    
+    nonzeroind = np.nonzero(resx)[0] # the return is a little funny so I use the [0]
+
+    nonzero_tup = np.unravel_index(nonzeroind, (L,L))
+
+    indx = nonzero_tup[0].tolist()
+    indy = nonzero_tup[1].tolist()
+    
+
+    verts = []
+
+    for i, x in enumerate(indx) :
+        verts.append((x, indy[i]))
+
+    
+    for vert in verts :
+        visited = []
+        visited.append(vert)
+
+        while len(visited) < n_edges + 1 :
+
+            try : 
+                ind = indx.index(vert[1])
+
+                vert = (indx[ind], indy[ind])
+
+                if vert in visited :
+                    return visited
+                else :
+                    visited.append(vert)
+            except :
+                break
+
+    return []
+
+# Constraint to not have d14 and d41 simultaneously. Does not prevent circular symmetry with more elements
 def break_sym(landmarks, A_ub, b_ub):
     L = len(landmarks)
     upper_ind = np.triu_indices(L,0,L)
@@ -125,6 +164,26 @@ def break_sym(landmarks, A_ub, b_ub):
 
     return A_ub, b_ub
 
+
+def prevent_circle(landmarks, A_ub, b_ub, circle) :
+    N = len(landmarks)
+    l = [0]*N*N
+
+    for index in circle :
+        x = index[0]
+        y = index[1]
+        l[x*N+y] = 1
+
+    A_ub = np.vstack((A_ub,l))
+    b_ub.append(len(circle)-1)
+
+    """print("\n\nPREVENT CIRCLE")
+    for i in range(7):
+        print(l[i*7:i*7+7])
+    print("\n")"""
+
+    return A_ub, b_ub
+
 # Constraint to respect max number of travels
 def respect_number(landmarks, A_ub, b_ub):
     h = []
@@ -152,9 +211,9 @@ def respect_order(landmarks: list, A_eq, b_eq):
             A_eq = np.vstack((A_eq,l))
             b_eq.append(0)
 
-            for i in range(7):
+            """for i in range(7):
                 print(l[i*7:i*7+7])
-            print("\n")
+            print("\n")"""
 
     return A_eq, b_eq
 
@@ -268,7 +327,19 @@ A_eq, b_eq = respect_order(landmarks, A_eq, b_eq)              # Respect order o
 x_bounds = [(0, 1)] * len(c)
 
 # Solve linear programming problem
+
 res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq = b_eq, bounds=x_bounds, method='highs', integrality=3)
+circle = has_circle(res.x)
+
+while len(circle) != 0 :
+    print("The solution has a circular path. Not interpretable.")
+    print("Need to add constraints until no circle ")
+
+    A_ub, b_ub = prevent_circle(landmarks, A_ub, b_ub, circle)
+    res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq = b_eq, bounds=x_bounds, method='highs', integrality=3)
+    circle = has_circle(res.x)
+
+
 
 # Raise error if no solution is found
 if not res.success :