refactor: use list accumulation instead of np.append in loop

np.append() copies the entire array on every iteration (O(n^2)).
List append + np.array at the end is O(n).

Author: pycckuu

porousmedialab/calibrator.py

@@ -21,12 +21,12 @@ def find_indexes_of_intersections(s, o, eps):
         idxs: indexes of simulated values
     """
 
-    idxs = np.array([])
+    idxs = []
     for o_i in o:
-        idx, = np.where(abs(s - o_i) <= eps*1.01)
+        idx, = np.where(abs(s - o_i) <= eps * 1.01)
         if idx.size > 0:
-            idxs = np.append(idxs, int(idx[0]))
-    return idxs.astype(int)
+            idxs.append(int(idx[0]))
+    return np.array(idxs, dtype=int)
 
 
 class Calibrator:

tests/test_calibrator.py

@@ -57,6 +57,42 @@ def test_first_match_used(self):
         assert len(idxs) == 1
         assert idxs[0] == 1  # First match
 
+    def test_large_input(self):
+        """Should work correctly with larger arrays."""
+        simulated = np.linspace(0, 10, 1001)
+        observed = np.array([1.0, 5.0, 9.0])
+        eps = 0.01
+
+        idxs = find_indexes_of_intersections(simulated, observed, eps)
+
+        assert len(idxs) == 3
+        # Verify values at found indexes are close to observed
+        for i, o_val in enumerate(observed):
+            assert abs(simulated[idxs[i]] - o_val) <= eps * 1.01
+
+    def test_returns_int_array(self):
+        """Return type should be numpy int array."""
+        simulated = np.array([0.0, 0.1, 0.2])
+        observed = np.array([0.1])
+        eps = 0.01
+
+        idxs = find_indexes_of_intersections(simulated, observed, eps)
+
+        assert isinstance(idxs, np.ndarray)
+        assert idxs.dtype == int
+
+    def test_empty_observed_returns_empty_int_array(self):
+        """Empty observed array should return empty int array."""
+        simulated = np.array([0.0, 0.1, 0.2])
+        observed = np.array([])
+        eps = 0.01
+
+        idxs = find_indexes_of_intersections(simulated, observed, eps)
+
+        assert isinstance(idxs, np.ndarray)
+        assert idxs.dtype == int
+        assert len(idxs) == 0
+
 
 class TestCalibratorInitialization:
     """Tests for Calibrator initialization."""