Fixes #11

tests/test_distances.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 import pytest
 
+from tsplib95 import models
 from tsplib95 import distances
 
 
@@ -56,7 +57,7 @@ def test_maximum(start, end, dist, exc):
     ((3, 4), (3, 4), 1, None),
     ((0, 0), (3, 4), 557, None),
     ((3, 4), (0, 0), 557, None),
-    ((-3, -4), (3, 4), 1218, None),
+    ((-3, -4), (3, 4), 1113, None),
     ((0, 1), (0, 1, 2), None, ValueError),
     ((0, 1, 2), (0, 1), None, ValueError),
 ])
@@ -66,3 +67,14 @@ def test_geographical(start, end, dist, exc):
             distances.geographical(start, end)
     else:
         assert distances.geographical(start, end) == dist
+
+
+@pytest.mark.parametrize('pfile,answer', [
+    ('data/pcb442.tsp', 221440),
+    ('data/gr666.tsp', 423710),
+    ('data/att532.tsp', 309636),
+])
+def test_verifcation_problems(read_problem_text, pfile, answer):
+    problem_text = read_problem_text(pfile)
+    problem = models.StandardProblem.parse(problem_text)
+    assert problem.trace_canonical_tour() == answer

tsplib95/distances.py

@@ -74,7 +74,7 @@ def geographical(start, end, round=utils.nint, radius=6378.388):
     q3 = math.cos(start.lat + end.lat)
     distance = radius * math.acos(0.5 * ((1 + q1) * q2 - (1 - q1) * q3)) + 1
 
-    return round(distance)
+    return int(distance)
 
 
 def pseudo_euclidean(start, end, round=utils.nint):
@@ -127,8 +127,8 @@ def xray(start, end, sx=1, sy=1, sz=1, round=utils.icost):
     'MAN_2D': manhattan,
     'MAN_3D': manhattan,
     'CEIL_2D': functools.partial(euclidean, round=math.ceil),
-    'GEO': euclidean,
-    'ATT': euclidean,
+    'GEO': geographical,
+    'ATT': pseudo_euclidean,
     'XRAY1': xray,
     'XRAY2': functools.partial(xray, sx=1.25, sy=1.5, sz=1.15),
 }

tsplib95/models.py

@@ -254,6 +254,10 @@ def trace_tours(self, solution):
             solutions.append(weight)
         return solutions
 
+    def trace_canonical_tour(self):
+        canonical_edges = utils.pairwise(self.get_nodes())
+        return sum(self.wfunc(i, j) for i, j in canonical_edges)
+
     def get_nodes(self):
         """Return an iterator over the nodes.
 

tsplib95/utils.py

@@ -9,7 +9,7 @@ def parse_degrees(coord):
     :return: real degrees
     :rtype: float
     """
-    degrees = nint(coord)
+    degrees = int(coord)
     minutes = coord - degrees
     return degrees + minutes * 5 / 3
 
@@ -58,9 +58,14 @@ def integer_sum(n, m=None):
 
 
 def pairwise(indexes):
+    # double list double in case indexes is an iterator
     starts = list(indexes)
-    ends = list(indexes)
+    ends = list(starts)
+
+    # shift the ends by one, and make it circular
     ends += [ends.pop(0)]
+
+    # pair up the neighbors
     return zip(starts, ends)