Fix to saving lattice map using the Grids GUI

armi/reactor/blueprints/gridBlueprint.py

@@ -265,7 +265,7 @@ def _constructSpatialGrid(self):
         runLog.extra("Creating the spatial grid")
         if geom in (geometry.RZT, geometry.RZ):
             if self.gridBounds is None:
-                # This check is regrattably late. It would be nice if we could validate
+                # This check is regrettably late. It would be nice if we could validate
                 # that bounds are provided if R-Theta mesh is being used.
                 raise InputError(
                     "Grid bounds must be provided for `{}` to specify a grid with "
@@ -580,27 +580,32 @@ def saveToStream(stream, bluep, full=False, tryMap=False):
         if gridDesign.readFromLatticeMap or tryMap:
             geomType = geometry.GeomType.fromStr(gridDesign.geom)
             symmetry = geometry.SymmetryType.fromStr(gridDesign.symmetry)
+
+            aMap = asciimaps.asciiMapFromGeomAndDomain(
+                gridDesign.geom, symmetry.domain
+            )()
+            aMap.asciiLabelByIndices = {
+                (key[0], key[1]): val for key, val in gridDesign.gridContents.items()
+            }
             try:
-                aMap = asciimaps.asciiMapFromGeomAndDomain(
-                    gridDesign.geom, symmetry.domain
-                )()
-                aMap.asciiLabelByIndices = {
-                    (key[0], key[1]): val
-                    for key, val in gridDesign.gridContents.items()
-                }
                 aMap.gridContentsToAscii()
             except Exception as e:
                 runLog.warning(
-                    "Cannot write geometry with asciimap. Defaulting to dict. Issue: {}".format(
-                        e
-                    )
+                    f"The `lattice map` for the current assembly arrangement cannot be written. "
+                    f"Defaulting to using the `grid contents` dictionary instead. Exception: {e}"
                 )
                 aMap = None
 
             if aMap is not None:
+                # If there is an ascii map available then use it to fill out
+                # the contents of the lattice map section of the grid design.
+                # This also clears out the grid contents so there is not duplicate
+                # data.
                 gridDesign.gridContents = None
+                mapString = StringIO()
+                aMap.writeAscii(mapString)
                 gridDesign.latticeMap = scalarstring.LiteralScalarString(
-                    gridDesign.latticeMap
+                    mapString.getvalue()
                 )
             else:
                 gridDesign.latticeMap = None

armi/reactor/blueprints/tests/test_gridBlueprints.py

@@ -294,6 +294,17 @@
             FP
 """
 
+TINY_GRID = """core:
+    geom: hex
+    lattice map:
+    grid bounds:
+    symmetry: full
+    grid contents:
+       ? - 0
+         - 0
+       : IF
+"""
+
 
 class TestRoundTrip(unittest.TestCase):
     def setUp(self):
@@ -309,6 +320,18 @@ def test_roundTrip(self):
         gridBp = Grids.load(stream)
         self.assertIn("third", gridBp["core"].symmetry)
 
+    def test_tiny_map(self):
+        grid = Grids.load(TINY_GRID)
+        stream = io.StringIO()
+        saveToStream(stream, grid, full=True, tryMap=True)
+        stream.seek(0)
+        text = stream.read()
+        self.assertIn("IF", text)
+        stream.seek(0)
+        gridBp = Grids.load(stream)
+        self.assertIn("full", gridBp["core"].symmetry)
+        self.assertIn("IF", gridBp["core"].latticeMap)
+
 
 class TestGridBlueprintsSection(unittest.TestCase):
     """Tests for lattice blueprint section."""

armi/utils/asciimaps.py

@@ -215,7 +215,7 @@ def gridContentsToAscii(self):
                 # doing pure rows from data is made programmatically.
                 # newLines.append(line)
                 raise ValueError(
-                    "Cannot write asciimaps with blank rows from pure data yet."
+                    f"Cannot write asciimaps with blank rows from pure data yet."
                 )
         if not newLines:
             raise ValueError("No data found")
@@ -434,12 +434,14 @@ def _updateDimensionsFromData(self):
         # Check the j=0 ray to see how many peripheral locations are blank.
         # assume symmetry with the other corner.
         # The cap is basically the distance from the (I, 0) or (0, J) loc to self._ijMax
-        maxIWithData = max(i for i, j in self.asciiLabelByIndices if j == 0)
+        iWithData = [i for i, j in self.asciiLabelByIndices if j == 0]
+        maxIWithData = max(iWithData) if iWithData else -1
         self._asciiLinesOffCorner = (self._ijMax - maxIWithData) * 2 - 1
 
         # in jagged systems we have to also check the neighbor.
         # TODO: maybe even more corner positions could be left out in very large maps.
-        nextMaxIWithData = max(i for i, j in self.asciiLabelByIndices if j == 1)
+        nextIWithData = [i for i, j in self.asciiLabelByIndices if j == 1]
+        nextMaxIWithData = max(nextIWithData) if nextIWithData else -1
         if nextMaxIWithData == maxIWithData - 1:
             # the jagged edge is lopped off too.
             self._asciiLinesOffCorner += 1

doc/release/0.2.rst

@@ -3,6 +3,15 @@ ARMI v0.2 Release Notes
 =======================
 
 
+ARMI v0.2.1
+===========
+Release Date: TBD
+
+
+Bug fixes
+---------
+* Fixed issue where grid GUI was not saving lattice maps (`#490 <https://github.com/terrapower/armi/issues/490>`_)
+
 
 ARMI v0.2.0
 ===========