Merge pull request gammapy#4852 from fabiopintore/tagevtid

Add flag to switch off MC identifiers in MapDatasetEventSampler

gammapy/datasets/simulate.py

@@ -31,14 +31,22 @@ class MapDatasetEventSampler:
         an energy-dependent time-varying source
     t_delta : `~astropy.units.Quantity`
         Time interval used to sample the time-dependent source
+    keep_mc_id : bool
+        Flag to tag sampled events from a given model with a Montecarlo identifier.
+        Default is True. If set to False, no identifier will be assigned
     """
 
     def __init__(
-        self, random_state="random-seed", oversample_energy_factor=10, t_delta=0.5 * u.s
+        self,
+        random_state="random-seed",
+        oversample_energy_factor=10,
+        t_delta=0.5 * u.s,
+        keep_mc_id=True,
     ):
         self.random_state = get_random_state(random_state)
         self.oversample_energy_factor = oversample_energy_factor
         self.t_delta = t_delta
+        self.keep_mc_id = keep_mc_id
 
     def _repr_html_(self):
         try:
@@ -264,13 +272,14 @@ def sample_sources(self, dataset):
                 npred = evaluator.apply_exposure(flux)
                 table = self._sample_coord_time(npred, temporal_model, dataset.gti)
 
-            if len(table) == 0:
-                mcid = table.Column(name="MC_ID", length=0, dtype=int)
-                table.add_column(mcid)
+            if self.keep_mc_id:
+                if len(table) == 0:
+                    mcid = table.Column(name="MC_ID", length=0, dtype=int)
+                    table.add_column(mcid)
 
-            table["MC_ID"] = idx + 1
-            table.meta["MID{:05d}".format(idx + 1)] = idx + 1
-            table.meta["MMN{:05d}".format(idx + 1)] = evaluator.model.name
+                table["MC_ID"] = idx + 1
+                table.meta["MID{:05d}".format(idx + 1)] = idx + 1
+                table.meta["MMN{:05d}".format(idx + 1)] = evaluator.model.name
 
             events_all.append(EventList(table))
 
@@ -295,13 +304,14 @@ def sample_background(self, dataset):
 
         table = self._sample_coord_time(background, temporal_model, dataset.gti)
 
-        table["MC_ID"] = 0
         table["ENERGY"] = table["ENERGY_TRUE"]
         table["RA"] = table["RA_TRUE"]
         table["DEC"] = table["DEC_TRUE"]
 
-        table.meta["MID{:05d}".format(0)] = 0
-        table.meta["MMN{:05d}".format(0)] = dataset.background_model.name
+        if self.keep_mc_id:
+            table["MC_ID"] = 0
+            table.meta["MID{:05d}".format(0)] = 0
+            table.meta["MMN{:05d}".format(0)] = dataset.background_model.name
 
         return EventList(table)
 
@@ -387,15 +397,19 @@ def event_det_coords(observation, events):
         return events
 
     @staticmethod
-    def event_list_meta(dataset, observation):
+    def event_list_meta(dataset, observation, keep_mc_id=True):
         """Event list meta info.
+        Please, note that this function will be updated in the future.
 
         Parameters
         ----------
         dataset : `~gammapy.datasets.MapDataset`
             Map dataset
         observation : `~gammapy.data.Observation`
             In memory observation
+        keep_mc_id : bool
+            Flag to tag sampled events from a given model with a Montecarlo identifier.
+            Default is True. If set to False, no identifier will be assigned
 
         Returns
         -------
@@ -476,7 +490,8 @@ def event_list_meta(dataset, observation):
         meta["CONV_RA"] = 0
         meta["CONV_DEC"] = 0
 
-        meta["NMCIDS"] = len(dataset.models)
+        if keep_mc_id:
+            meta["NMCIDS"] = len(dataset.models)
 
         # Necessary for DataStore, but they should be ALT and AZ instead!
         telescope = observation.aeff.meta["TELESCOP"]
@@ -555,7 +570,9 @@ def run(self, dataset, observation=None):
 
         events = self.event_det_coords(observation, events)
         events.table["EVENT_ID"] = np.arange(len(events.table))
-        events.table.meta.update(self.event_list_meta(dataset, observation))
+        events.table.meta.update(
+            self.event_list_meta(dataset, observation, self.keep_mc_id)
+        )
 
         geom = dataset._geom
         selection = geom.contains(events.map_coord(geom))

gammapy/datasets/tests/test_simulate.py

@@ -780,3 +780,60 @@ def test_MC_ID_NMCID(model_alternative):
     assert meta["MID00002"] == 2
     assert meta["MID00003"] == 3
     assert meta["NMCIDS"] == 4
+
+
+@requires_data()
+def test_MC_ID_flag(model_alternative):
+    irfs = load_irf_dict_from_file(
+        "$GAMMAPY_DATA/cta-1dc/caldb/data/cta/1dc/bcf/South_z20_50h/irf_file.fits"
+    )
+    livetime = 0.1 * u.hr
+    skydir = SkyCoord(0, 0, unit="deg", frame="galactic")
+    pointing = FixedPointingInfo(fixed_icrs=skydir.icrs)
+    obs = Observation.create(
+        obs_id=1001,
+        pointing=pointing,
+        livetime=livetime,
+        irfs=irfs,
+        location=LOCATION,
+    )
+
+    energy_axis = MapAxis.from_energy_bounds(
+        "1.0 TeV", "10 TeV", nbin=10, per_decade=True
+    )
+    energy_axis_true = MapAxis.from_energy_bounds(
+        "0.5 TeV", "20 TeV", nbin=20, per_decade=True, name="energy_true"
+    )
+    migra_axis = MapAxis.from_bounds(0.5, 2, nbin=150, node_type="edges", name="migra")
+
+    geom = WcsGeom.create(
+        skydir=skydir,
+        width=(2, 2),
+        binsz=0.06,
+        frame="icrs",
+        axes=[energy_axis],
+    )
+
+    empty = MapDataset.create(
+        geom,
+        energy_axis_true=energy_axis_true,
+        migra_axis=migra_axis,
+        name="test",
+    )
+    maker = MapDatasetMaker(selection=["exposure", "background", "psf", "edisp"])
+    dataset = maker.run(empty, obs)
+
+    model_alternative[0].spectral_model.parameters["amplitude"].value = 1e-16
+    dataset.models = model_alternative
+    sampler = MapDatasetEventSampler(random_state=0, keep_mc_id=False)
+    events = sampler.run(dataset=dataset, observation=obs)
+
+    meta = events.table.meta
+    assert len(events.table) == 47
+    assert "MC_ID" not in events.table.colnames
+    assert "MID00000" not in meta.keys()
+    assert "MMN00000" not in meta.keys()
+    assert "MID00001" not in meta.keys()
+    assert "MID00002" not in meta.keys()
+    assert "MID00003" not in meta.keys()
+    assert "NMCIDS" not in meta.keys()