Merge pull request #17 from dslosky-usgs/updates

Fix intersection and add test for intersection

setup.py

@@ -29,7 +29,7 @@
     # Versions should comply with PEP440.  For a discussion on single-sourcing
     # the version across setup.py and the project code, see
     # https://packaging.python.org/en/latest/single_source_version.html
-    version='0.0a4',
+    version='0.0a5',
 
     description='Potential impact calculation for well defined facilities due to an input earthquake hazard',
     long_description=long_description,

shakecastaebm/performance_point.py

@@ -54,8 +54,8 @@ def get_intersection(seg1, seg2, x, y):
                 (dy2 * dx1 - dx2 * dy1))
 
     if (s >= 0 and s <= 1 and t >= 0 and t <= 1):
-        x_val = abs(round(seg1[0][x] + t * dx1 * 1000) / 1000)
-        y_val = abs(round(seg1[0][y] + t * dy1 * 1000) / 1000)
+        x_val = abs(round((seg1[0][x] + t * dx1) * 1000) / 1000)
+        y_val = abs(round((seg1[0][y] + t * dy1) * 1000) / 1000)
         return {x: x_val, y: y_val}
     else:
       return False

shakecastaebm/tests/performance_point.py

@@ -21,6 +21,33 @@ def test_performancePoint(self):
         self.assertTrue('acc' in pp.keys())
         self.assertTrue('period' in pp.keys())
 
+    def test_intersection(self):
+        capacity = [
+            {'disp': 1, 'acc': .1},
+            {'disp': 2, 'acc': 1}
+        ]
+        demand = [
+            {'disp': 1, 'acc': 1},
+            {'disp': 2, 'acc': .1}
+        ]
+
+        pp = get_performance_point(capacity, demand)[0]
+
+        # slopes for the intersection with the demand
+        dem_slope1 = ((demand[0]['acc'] - pp['acc']) /
+                (demand[0]['disp'] - pp['disp']))
+        dem_slope2 = ((demand[1]['acc'] - pp['acc']) /
+                (demand[1]['disp'] - pp['disp']))
+
+        # slopes for intersection with capacity
+        cap_slope1 = ((capacity[0]['acc'] - pp['acc']) /
+                (capacity[0]['disp'] - pp['disp']))
+        cap_slope2 = ((capacity[1]['acc'] - pp['acc']) /
+                (capacity[1]['disp'] - pp['disp']))
+
+        self.assertAlmostEqual(dem_slope1, dem_slope2)
+        self.assertAlmostEqual(cap_slope1, cap_slope2)
+
 
 if __name__ == '__main__':
-    unittest.main()
+    unittest.main()