Merge pull request gammapy#5438 from fabiopintore/bottleneck

Speed up event sampler

gammapy/datasets/simulate.py

@@ -248,27 +248,34 @@ def _sample_coord_time(self, npred, temporal_model, gti):
 
         return table
 
-    def sample_sources(self, dataset):
+    def sample_sources(self, dataset, psf_update=False):
         """Sample source model components.
 
         Parameters
         ----------
         dataset : `~gammapy.datasets.MapDataset`
             Map dataset.
+        psf_update : bool
+            Parameter to switch-off (on) the update of the PSF
+            in the dataset; default is False.
 
         Returns
         -------
         events : `~gammapy.data.EventList`
             Event list.
         """
+        if psf_update is True:
+            psf_update = dataset.psf
+        else:
+            psf_update = None
 
         events_all = EventList(Table())
         for idx, evaluator in enumerate(dataset.evaluators.values()):
             log.info(f"Evaluating model: {evaluator.model.name}")
             if evaluator.needs_update:
                 evaluator.update(
                     dataset.exposure,
-                    dataset.psf,
+                    psf_update,
                     dataset.edisp,
                     dataset._geom,
                     dataset.mask,

gammapy/datasets/tests/test_simulate.py

@@ -354,6 +354,14 @@ def test_mde_sample_sources(dataset, models):
     assert_allclose(events.table["MC_ID"][0], 1, rtol=1e-5)
 
 
+@requires_data()
+def test_mde_sample_sources_psf_update(dataset, models):
+    dataset.models = models
+    sampler = MapDatasetEventSampler(random_state=0)
+    events = sampler.sample_sources(dataset=dataset, psf_update=False)
+    assert len(events.table["ENERGY_TRUE"]) == 90
+
+
 @requires_data()
 def test_sample_sources_energy_dependent(dataset, energy_dependent_temporal_sky_model):
     dataset.models = energy_dependent_temporal_sky_model