Merge pull request #2552 from cta-observatory/fix_stereo_trigger_prod6

Fix StereoTrigger non-deterministically discarding LST-1 in prod6 files

Author: maxnoe

docs/changes/2552.bugfix.rst

@@ -0,0 +1,6 @@
+Fix ``SoftwareTrigger`` not correctly handling different telescope
+types that have the same string representation, e.g. the four LSTs
+in prod6 files.
+
+Telescopes that have the same string representation now always are treated
+as one group in ``SoftwareTrigger``.

src/ctapipe/instrument/tests/test_trigger.py

@@ -1,10 +1,12 @@
 import json
+from copy import deepcopy
 
 import numpy as np
 import pytest
 from numpy.testing import assert_equal
 
 from ctapipe.containers import ArrayEventContainer
+from ctapipe.instrument import SubarrayDescription
 from ctapipe.io import EventSource
 
 
@@ -235,3 +237,68 @@ def test_software_trigger_simtel_process(tmp_path):
         )
 
     assert len(events_no_trigger) > len(events_trigger)
+
+
+def test_different_telescope_type_same_string(subarray_prod5_paranal):
+    """
+    Test that for a subarray that contains two different telescope types
+    with the same string representation, the subarray trigger is working
+    as expected, treating these telescopes as a single group.
+    """
+    from ctapipe.instrument.trigger import SoftwareTrigger
+
+    lst234 = deepcopy(subarray_prod5_paranal.tel[2])
+    # make LST-1 slightly different from LSTs 2-4
+    lst1 = deepcopy(subarray_prod5_paranal.tel[1])
+    lst1.optics.mirror_area *= 0.9
+
+    assert lst1 != lst234
+
+    subarray = SubarrayDescription(
+        name="test",
+        tel_positions={
+            tel_id: subarray_prod5_paranal.positions[tel_id] for tel_id in (1, 2, 3, 4)
+        },
+        tel_descriptions={
+            1: lst1,
+            2: lst234,
+            3: lst234,
+            4: lst234,
+        },
+        reference_location=subarray_prod5_paranal.reference_location,
+    )
+
+    trigger = SoftwareTrigger(
+        subarray=subarray,
+        min_telescopes=2,
+        min_telescopes_of_type=[
+            ("type", "*", 0),
+            ("type", "LST*", 2),
+        ],
+    )
+
+    # all four LSTs, nothing to change
+    event = ArrayEventContainer()
+    event.trigger.tels_with_trigger = [1, 2, 3, 4]
+    assert trigger(event)
+    assert_equal(event.trigger.tels_with_trigger, [1, 2, 3, 4])
+
+    # two LSTs, nothing to change
+    event = ArrayEventContainer()
+    event.trigger.tels_with_trigger = [1, 2]
+    assert trigger(event)
+    assert_equal(event.trigger.tels_with_trigger, [1, 2])
+
+    # two LSTs, nothing to change
+    event = ArrayEventContainer()
+    event.trigger.tels_with_trigger = [1, 3]
+    assert trigger(event)
+    assert_equal(event.trigger.tels_with_trigger, [1, 3])
+
+    # one LST, remove
+    event = ArrayEventContainer()
+    event.trigger.tels_with_trigger = [
+        1,
+    ]
+    assert not trigger(event)
+    assert_equal(event.trigger.tels_with_trigger, [])

src/ctapipe/instrument/trigger.py

@@ -59,10 +59,16 @@ class SoftwareTrigger(TelescopeComponent):
     def __init__(self, subarray, *args, **kwargs):
         super().__init__(subarray, *args, **kwargs)
 
-        self._ids_by_type = {
-            str(type): set(self.subarray.get_tel_ids_for_type(type))
-            for type in self.subarray.telescope_types
-        }
+        # we are grouping telescopes by the str repr of the type
+        # this is needed since e.g. in prod6, LST-1 is slightly different
+        # from LST-2 to LST-4, but we still want the trigger to work with all
+        # LSTs
+        self._ids_by_type = {}
+        for tel in self.subarray.telescope_types:
+            tel_str = str(tel)
+            if tel_str not in self._ids_by_type:
+                self._ids_by_type[tel_str] = set()
+            self._ids_by_type[tel_str].update(self.subarray.get_tel_ids_for_type(tel))
 
     def __call__(self, event: ArrayEventContainer) -> bool:
         """
@@ -79,24 +85,22 @@ def __call__(self, event: ArrayEventContainer) -> bool:
         """
 
         tels_removed = set()
-        for tel_type in self.subarray.telescope_types:
-            tel_type_str = str(tel_type)
-            min_tels = self.min_telescopes_of_type.tel[tel_type_str]
+        for tel_type, tel_ids in self._ids_by_type.items():
+            min_tels = self.min_telescopes_of_type.tel[tel_type]
 
             # no need to check telescopes for which we have no min requirement
             if min_tels == 0:
                 continue
 
             tels_with_trigger = set(event.trigger.tels_with_trigger)
-            tel_ids = self._ids_by_type[tel_type_str]
             tels_in_event = tels_with_trigger.intersection(tel_ids)
 
             if len(tels_in_event) < min_tels:
                 for tel_id in tels_in_event:
                     self.log.debug(
                         "Removing tel_id %d of type %s from event due to type requirement",
                         tel_id,
-                        tel_type_str,
+                        tel_type,
                     )
 
                     # remove from tels_with_trigger

src/ctapipe/tools/process.py

@@ -301,7 +301,6 @@ def start(self):
             disable=not self.progress_bar,
         ):
             self.log.debug("Processing event_id=%s", event.index.event_id)
-
             if not self.event_type_filter(event):
                 continue