fix: count_ratio on non overlapping partitions

bsb/placement/indicator.py

@@ -97,12 +97,10 @@ def guess(self, chunk=None, voxels=None):
             relation = relative_to
             if count_ratio is not None:
                 strats = self._strat.scaffold.get_placement_of(relation)
-                estimate = (
-                    sum(
-                        PlacementIndicator(s, relation).guess(chunk, voxels)
-                        for s in strats
-                    )
-                    * count_ratio
+                estimate = self._estim_for_chunk(
+                    chunk,
+                    sum(PlacementIndicator(s, relation).guess() for s in strats)
+                    * count_ratio,
                 )
             elif density_ratio is not None:
                 # Create an indicator based on this strategy for the related CT.

tests/test_placement.py

@@ -21,6 +21,7 @@
     PlacementError,
     PlacementRelationError,
     PlacementStrategy,
+    Rhomboid,
     Scaffold,
     VoxelData,
     Voxels,
@@ -222,6 +223,25 @@ def test_guess_vox_density(self):
             # voxel density key not found
             dud4_ind.guess(voxels=self.voxels.get_voxelset())
 
+    def test_regression_issue_885(self):
+        # Test placement with count ratio in separated partitions
+        self.network.topology.children.append(
+            part := Rhomboid(
+                name="dud_layer2", origin=[0, 0, 120], dimensions=[200, 200, 80]
+            )
+        )
+        self.network.resize()
+        placement = PlacementDud(
+            name="dud",
+            strategy="PlacementDud",
+            partitions=[part],
+            cell_types=[self.network.cell_types["cell_rel_count"]],
+        )
+        self.network.placement["dud3"] = placement
+        indic = placement.get_indicators()["cell_rel_count"]
+        self.assertEqual(20 / 4, indic.guess(_chunk(0, 0, 1)))
+        self.assertEqual(20 / 4, indic.guess(_chunk(1, 1, 1)))
+
     def test_negative_guess_count(self):
         self.placement = single_layer_placement(
             self.network, offset=np.array([-300.0, -300.0, -300.0])