fixed inconsistencies in returned objects: missing channels, is_clipped

tests/test_Accumulation.py

@@ -107,6 +107,35 @@ class TestAccumulation(unittest.TestCase):
         self.assertEqual(sub_result.index, [(0, 1)])
         self.assertEqual(sub_result.common_descriptions, {"key": "value"})
 
+    def test_get_accu_by_index_copies_is_clipped(self):
+        """Test that get_accu_by_index properly copies is_clipped."""
+        adc = self.create_adc_result()
+        adc.index = [(0, 1), (1, 2)]
+        accu = Accumulation()
+        accu += adc
+        accu.is_clipped = True
+
+        sub_result = accu.get_accu_by_index(1)
+
+        self.assertEqual(sub_result.is_clipped, True)
+
+    def test_get_accu_by_index_data_independence(self):
+        """Test that get_accu_by_index returns independent data (not shared views)."""
+        adc = self.create_adc_result()
+        adc.index = [(0, 1), (1, 2)]
+        accu = Accumulation()
+        accu += adc
+        original_y0 = accu.y[0].copy()
+
+        sub_result = accu.get_accu_by_index(1)
+        sub_result.y[0][0] = 9999
+        sub_result.x[0] = 999.0
+
+        self.assertEqual(sub_result.y[0][0], 9999)
+        self.assertTrue(np.array_equal(accu.y[0], original_y0))
+        # x array should also be independent
+        self.assertEqual(accu.x[1], 1.0)
+
     def test_write_to_csv_without_error(self):
         """Test the functionality of writing to CSV."""
         from io import StringIO