Update default importance values to 1.0 in Importance class and tests

doc/source/changelog.rst

@@ -18,17 +18,15 @@ MontePy Changelog
 * Allow multiple universe fills to accept 2D MNCP lattices (:issue:`719`).
 * Make `LatticeType.RECTANGULAR` and `LatticeType.HEXAHEDRAL` synonymous (:issue:`808`).
 * Allow setting ``cell.fill.universes`` with a numpy array of universe IDs (:issue:`736`).
+* Added Boundary condition type to the representation of a ``montepy.Surface`` (e.g., ``repr(surf)``)  (:issue:`682`).
+* Changed default importance value from 0.0 to 1.0 to match MCNP defaults. (:issue:`735`)
 
 **Bugs Fixed**
 
 * Fixed bug where lines that were the allowed length was raising a ``LineOverRunWarning`` when read by MontePy (:issue:`517`). 
 * Added descriptive TypeError messages (:issue:`801`)
 * Fixed a bug that caused to write an extra termination line between the data block and the cell data section in the MCNP input. (:pull:`819`) (:issue:`703`).
 
-**Documentation**
-
-* Improved documentation for NumberedObjectCollections on Slicing behavior. (:issue:`798`)
-
 **Deprecations**
 
 * Dropped support for python 3.9 through 3.11, and numpy 1.26 in order to comply with `SPEC 0 <https://scientific-python.org/specs/spec-0000/>`_ (:issue:`780`).
@@ -42,9 +40,7 @@ MontePy Changelog
 
 1.1.3
 --------------
-**Features Added**
 
-* Added Boundary condition type to the representation of a ``montepy.Surface`` (e.g., ``repr(surf)``)  (:issue:`682`).
 
 **Documentation**
 

doc/source/starting.rst

@@ -609,10 +609,10 @@ For example:
 
     >>> for particle in sorted(problem.mode):
     ...     print(particle, cell.importance[particle])
-    neutron 0.0
-    photon 0.0
+    neutron 1.0
+    photon 1.0
     >>> print(cell.importance[montepy.Particle.NEUTRON])
-    0.0
+    1.0
 
 There's also a lot of convenient ways to do bulk modifications.
 There is the :func:`~montepy.data_inputs.importance.Importance.all` property that lets you set the importance for all particles in the problem at once.
@@ -629,7 +629,10 @@ For example:
     neutron 2.0
     photon 2.0
 
-This will set the importances for the neutron and photon. 
+This will set the importances for the neutron and photon.
+
+You can also delete an importance to reset it to the default value (1.0).
+For example: ``del cell.importance.neutron``.
 
 There is also the method: :func:`~montepy.cells.Cells.set_equal_importance`.
 This method sets all of the cells for all particles in the problem to the same importance.

montepy/cell.py

@@ -227,10 +227,17 @@ def importance(self):
         Each particle's importance is a property of Importance.
         e.g., ``cell.importance.photon = 1.0``.
 
+        Deleting an importance resets it to the default value (1.0).
+        e.g., ``del cell.importance.neutron``.
+
         Returns
         -------
         Importance
             the importance for the Cell.
+
+        .. versionchanged:: 1.2.0
+
+            Default importance value changed from 0.0 to 1.0 to match MCNP defaults.
         """
         return self._importance
 

montepy/data_inputs/importance.py

@@ -42,6 +42,8 @@ class Importance(CellModifierInput):
         the value syntax tree from the key-value pair in a cell
     """
 
+    _DEFAULT_IMP = 1.0
+
     def __init__(
         self,
         input: InitInput = None,
@@ -52,6 +54,7 @@ def __init__(
         self._particle_importances = {}
         self._real_tree = {}
         self._part_combos = []
+        self._explicitly_set = False
         super().__init__(input, in_cell_block, key, value)
         if self.in_cell_block:
             if key:
@@ -62,6 +65,7 @@ def __init__(
                     raise ValueError(
                         f"Cell importance must be a number ≥ 0. {val.value} was given"
                     )
+                self._explicitly_set = True
                 self._part_combos.append(self.particle_classifiers)
                 for particle in self.particle_classifiers:
                     self._particle_importances[particle] = value
@@ -76,6 +80,7 @@ def __init__(
                     raise MalformedInputError(
                         input, f"Importances must be ≥ 0 value: {node} given"
                     )
+            self._explicitly_set = True
             self._part_combos.append(self.particle_classifiers)
             for particle in self.particle_classifiers:
                 self._particle_importances[particle] = copy.deepcopy(self._tree)
@@ -95,7 +100,7 @@ def _generate_default_cell_tree(self, particle=None):
             particles.particles = self._problem.mode.particles
         classifier.particles = particles
         list_node = syntax_node.ListNode("imp data")
-        list_node.append(self._generate_default_node(float, 0.0))
+        list_node.append(self._generate_default_node(float, self._DEFAULT_IMP))
         tree = syntax_node.SyntaxNode(
             "Importance",
             {
@@ -125,8 +130,17 @@ def _has_classifier():
 
     @property
     def has_information(self):
-        if self.in_cell_block:
+        has_info = []
+        for part in self:
+            has_info.append(
+                not math.isclose(
+                    self[part], self._DEFAULT_IMP, rel_tol=rel_tol, abs_tol=abs_tol
+                )
+            )
+        if any(has_info):
             return True
+        if self.in_cell_block:
+            return self.set_in_cell_block
 
     def merge(self, other):
         if not isinstance(other, type(self)):
@@ -163,7 +177,7 @@ def __getitem__(self, particle):
             val = self._particle_importances[particle]["data"][0]
             return val.value
         except KeyError:
-            return 0.0
+            return self._DEFAULT_IMP
 
     def __setitem__(self, particle, value):
         if not isinstance(particle, Particle):
@@ -175,6 +189,7 @@ def __setitem__(self, particle, value):
             raise ValueError("importance must be ≥ 0")
         if particle not in self._particle_importances:
             self._generate_default_cell_tree(particle)
+        self._explicitly_set = True
         self._particle_importances[particle]["data"][0].value = value
 
     def __delitem__(self, particle):
@@ -213,6 +228,7 @@ def push_to_cells(self):
                     value = self._particle_importances[particle]["data"][i]
                     # force generating the default tree
                     cell.importance[particle] = value.value
+                    cell.importance._explicitly_set = True
                     # replace default ValueNode with actual valueNode
                     tree = cell.importance._particle_importances[particle]
                     tree.nodes["classifier"] = copy.deepcopy(
@@ -284,6 +300,7 @@ def all(self, value):
         if value < 0.0:
             raise ValueError("Importance must be ≥ 0.0")
         if self._problem:
+            self._explicitly_set = True
             for particle in self._problem.mode:
                 self._particle_importances[particle]["data"][0].value = value
 
@@ -506,7 +523,7 @@ def __create_particle_imp_doc(particle_type):
 Returns
 -------
 float
-    the importance for the particle type. If not set, defaults to 0.
+    the importance for the particle type. If not set, defaults to 1.0.
 """
 
 

pyproject.toml

@@ -14,7 +14,8 @@ authors = [
 	{name = "Brenna Carbno", email="[email protected]"},
 	{name = "Benjaminas Marcinkevicius", email="[email protected]"},
 	{name = "Paul Ferney", email="[email protected]"},
-	{name = "Digvijay Yeware", email="[email protected]"}
+	{name = "Digvijay Yeware", email="[email protected]"},
+	{name = "Harsh Dayal", email="[email protected]"},
 ]
 keywords = ["MCNP", "neutronics", "imcnp", "input file", "monte carlo", "radiation transport"]
 license = "MIT"

tests/test_importance.py

@@ -28,7 +28,7 @@ def create_cell_from_input(self, in_str, block=block_type.BlockType.CELL):
                     "neutron": 1.0,
                     "photon": 1.0,
                     "all": None,
-                    "alpha_particle": 0.0,
+                    "alpha_particle": 1.0,
                     "in_cell_block": True,
                 },
                 None,
@@ -40,7 +40,7 @@ def create_cell_from_input(self, in_str, block=block_type.BlockType.CELL):
             ),
             (
                 "1 0 -1",
-                {"neutron": 0.0},
+                {"neutron": 1.0},
                 None,
             ),  # default neutron importance when nothing is set
             # Error cases
@@ -267,9 +267,9 @@ def test_importance_deleter(self, cell_with_importance):
         """
         cell = cell_with_importance
         del cell.importance.neutron
-        assert cell.importance.neutron == pytest.approx(0.0)
+        assert cell.importance.neutron == pytest.approx(1.0)
         del cell.importance[Particle.PHOTON]
-        assert cell.importance.photon == pytest.approx(0.0)
+        assert cell.importance.photon == pytest.approx(1.0)
         with pytest.raises(TypeError):
             del cell.importance[""]
 
@@ -312,3 +312,8 @@ def test_default_importance_not_implemented(self):
         prob.print_in_data_block["imp"] = True
         with pytest.raises(NotImplementedError):
             prob.write_problem(io.StringIO())
+
+    def test_default_cell_importance(self):
+        """Test that new cells have default importance of 1.0 (Issue #735)"""
+        cell = montepy.Cell()
+        assert cell.importance.neutron == 1.0

tests/test_integration.py

@@ -1120,9 +1120,15 @@ def test_alternate_encoding():
     )
 
 
+"""
+file_path: {line_number (0-indexed): flag}
+
+Flags: 
+    0: skip line in both files
+    1: skip line in output file
+    2+: skip line in gold file
+"""
 _SKIP_LINES = {
-    # skip lines of added implied importances
-    "tests/inputs/test_universe_data.imcnp": {5: 1, 14: 1, 15: 1},
     # I don't care about the edge case of shortcuts in a material def.
     "tests/inputs/test_complement_edge.imcnp": {37: 0, 38: 0, 39: 0},
 }
@@ -1141,6 +1147,11 @@ def test_alternate_encoding():
     },
 )
 def test_read_write_cycle(file):
+    """
+    Warning: this test is a Rube Goldberg machine of edge cases.
+
+    Please ask @micahgale before modifying it.
+    """
     print(f"Testing against {file} *********************")
     if ".swp" in file.suffixes:
         return

tests/test_universe_integration.py

@@ -119,7 +119,11 @@ def test_fill_multi_universe_order(cells):
         cell.fill.universes = unis
         output = cell.format_for_mcnp_input((6, 2, 0))
         words = " ".join(output).split()
-        new_universes = list(map(int, words[7:]))
+        start_idx = 6
+        if "imp:n=1" in words:
+            start_idx += 1
+        print(output)
+        new_universes = list(map(int, words[start_idx:]))
         assert (numbers.flatten("f") == new_universes).all()