Mcstas instrument geometry in the loader.

docs/examples/workflow.ipynb

@@ -9,7 +9,8 @@
  "## Collect Parameters and Providers\n",
  "### Simulation(McStas) Data\n",
  "There is a dedicated loader, ``load_mcstas_nexus`` for ``McStas`` simulation data workflow. <br>\n",
- "``MaximumProbability`` can be manually provided to the loader to derive more realistic number of events. <br>\n",
+ "``MaximumProbability`` can be manually provided to the loader <br>\n",
+ "to derive more realistic number of events. <br>\n",
  "It is because ``weights`` are given as probability, not number of events in a McStas file. <br>"
  ]
  },
@@ -47,7 +48,9 @@
  "source": [
  "from typing import get_type_hints\n",
  "param_reprs = {key.__name__: value for key, value in params.items()}\n",
- "prov_reprs = {get_type_hints(prov)['return'].__name__: prov.__name__ for prov in providers}\n",
+ "prov_reprs = {\n",
+ " get_type_hints(prov)['return'].__name__: prov.__name__ for prov in providers\n",
+ "}\n",
  "\n",
  "# Providers and parameters to be used for pipeline\n",
  "sc.DataGroup(**prov_reprs, **param_reprs)"
@@ -91,11 +94,38 @@
  "da = nmx_workflow.compute(NMXData)\n",
  "da"
  ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Instrument View\n",
+ "\n",
+ "Pixel positions are not used for later steps,\n",
+ "but it is included in the coordinates for instrument view.\n",
+ "\n",
+ "All pixel positions are relative to the sample position,\n",
+ "therefore the sample is at (0, 0, 0).\n",
+ "\n",
+ "You can plot the instrument view like below.\n",
+ "\n",
+ "```python\n",
+ "import scippneutron as scn\n",
+ "\n",
+ "unnecessary_coords = list(coord for coord in da.coords if coord != 'position')\n",
+ "instrument_view_da = da.drop_coords(unnecessary_coords).flatten(['panel', 'id'], 'id').hist()\n",
+ "view = scn.instrument_view(instrument_view_da)\n",
+ "view.children[0].toolbar.cameraz()\n",
+ "view\n",
+ "```\n",
+ "\n",
+ "**It might be very slow or not work in the ``VS Code`` jupyter notebook editor.**"
+ ]
  }
  ],
  "metadata": {
  "kernelspec": {
- "display_name": "nmx-dev-39",
+ "display_name": "Python 3 (ipykernel)",
  "language": "python",
  "name": "python3"
  },
@@ -113,5 +143,5 @@
  }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }

src/ess/nmx/mcstas_loader.py

@@ -7,7 +7,7 @@
 
 PixelIDs = NewType("PixelIDs", sc.Variable)
 InputFilepath = NewType("InputFilepath", str)
-NMXData = NewType("NMXData", sc.DataArray)
+NMXData = NewType("NMXData", sc.DataGroup)
 
 # McStas Configurations
 MaximumProbability = NewType("MaximumProbability", int)
@@ -37,13 +37,6 @@ def _copy_partial_var(
  return var
 
 
-def _get_mcstas_pixel_ids() -> PixelIDs:
- """pixel IDs for each detector"""
- intervals = [(1, 1638401), (2000001, 3638401), (4000001, 5638401)]
- ids = [sc.arange('id', start, stop, unit=None) for start, stop in intervals]
- return PixelIDs(sc.concat(ids, 'id'))
-
-
 def load_mcstas_nexus(
  file_path: InputFilepath,
  max_probability: Optional[MaximumProbability] = None,
@@ -60,6 +53,9 @@ def load_mcstas_nexus(
 
  """
 
+ from .mcstas_xml import read_mcstas_geometry_xml
+
+ geometry = read_mcstas_geometry_xml(file_path)
  probability = max_probability or DefaultMaximumProbability
 
  with snx.File(file_path) as file:
@@ -76,6 +72,9 @@ def load_mcstas_nexus(
  weights = (probability / weights.max()) * weights
 
  loaded = sc.DataArray(data=weights, coords={'t': t_list, 'id': id_list})
- grouped = loaded.group(_get_mcstas_pixel_ids())
+ coords = geometry.to_coords()
+ grouped = loaded.group(coords.pop('pixel_id'))
+ da = grouped.fold(dim='id', sizes={'panel': len(geometry.detectors), 'id': -1})
+ da.coords.update(coords)
 
- return NMXData(grouped.fold(dim='id', sizes={'panel': 3, 'id': -1}))
+ return NMXData(da)