Implement reading of simulated event distribution in HDF5EventSource, f…

…ixes #2632

src/ctapipe/io/hdf5eventsource.py

@@ -35,6 +35,7 @@
     SchedulingBlockContainer,
     SimulatedEventContainer,
     SimulatedShowerContainer,
+    SimulatedShowerDistribution,
     SimulationConfigContainer,
     TelescopeImpactParameterContainer,
     TelescopePointingContainer,
@@ -231,6 +232,24 @@ def __init__(self, input_url=None, config=None, parent=None, **kwargs):
                 table.add_index("obs_id")
                 self._constant_telescope_pointing[tel_id] = table
 
+        self._simulated_shower_distributions = (
+            self._read_simulated_shower_distributions()
+        )
+
+    def _read_simulated_shower_distributions(self):
+        key = "/simulation/service/shower_distribution"
+        if key not in self.file_.root:
+            return {}
+
+        reader = HDF5TableReader(self.file_).read(
+            key, containers=SimulatedShowerDistribution
+        )
+        return {dist.obs_id: dist for dist in reader}
+
+    @property
+    def simulated_shower_distributions(self):
+        return self._simulated_shower_distributions
+
     def __exit__(self, exc_type, exc_val, exc_tb):
         self.close()
 

src/ctapipe/io/tests/test_hdf5eventsource.py

@@ -262,3 +262,11 @@ def test_interpolate_pointing(dl1_mon_pointing_file):
             for pointing in e.pointing.tel.values():
                 assert not np.isnan(pointing.azimuth)
                 assert not np.isnan(pointing.altitude)
+
+
+def test_simulated_events_distribution(dl1_file):
+    with HDF5EventSource(dl1_file) as source:
+        assert len(source.simulated_shower_distributions) == 1
+        dist = source.simulated_shower_distributions[1]
+        assert dist["n_entries"] == 1000
+        assert dist["histogram"].sum() == 1000.0