Merge pull request #704 from scipp/check-coords-instrument-view

Check coords are identical in slicing dimension in instrument view

Author: nvaytet

src/scippneutron/instrument_view.py

@@ -14,10 +14,18 @@ def _to_data_array(
     if isinstance(data, sc.DataArray):
         data = sc.DataGroup({"": data})
     pieces = []
+    dim_coord = None
     for da in data.values():
         da = da.drop_coords(list(set(da.coords) - {pos, dim}))
         position_dims = tuple(da.coords[pos].dims)
         if dim is not None:
+            if dim_coord is None:
+                dim_coord = da.coords[dim]
+            elif not sc.identical(dim_coord, da.coords[dim]):
+                raise ValueError(
+                    "All inputs must have the same coordinate along the slider"
+                    f" dimension '{dim}'."
+                )
             # Ensure that the dims to be flattened are contiguous, and place them at
             # the end so that slicing the first (outer) dim with the slider is
             # efficient.

tests/instrument_view_test.py

@@ -3,6 +3,7 @@
 
 import matplotlib
 import numpy as np
+import pytest
 import scipp as sc
 
 import scippneutron as scn
@@ -92,3 +93,17 @@ def test_neutron_instrument_view_with_masks():
 def test_neutron_instrument_view_with_cmap_args():
     bank = make_detector_bank(center=(0, 0, 5))
     scn.instrument_view(bank, size=0.1, vmin=10.0, vmax=50.0, cmap="magma", logc=True)
+
+
+def test_instrument_view_two_banks_dict_with_dim_different_coords_raises():
+    bank1 = make_detector_bank(center=(-1.5, 0, 5))
+    bank2 = make_detector_bank(center=(1.5, 0, 5))
+    bank2.coords['time'] *= 1.01
+    bank3 = make_detector_bank(center=(1.5, 0, 5))
+    with pytest.raises(
+        ValueError,
+        match="All inputs must have the same coordinate along the slider dimension",
+    ):
+        scn.instrument_view(
+            {"bank1": bank1, "bank2": bank2, "bank3": bank3}, size=0.1, dim='time'
+        )