Hackish fix to be able to load last halo.

Author: kyleaoman

velociraptor/particles/particles.py

@@ -132,15 +132,23 @@ def extract_halo(self, halo_index: int, filenames: Union[Dict[str, str], None] =
             unbound_particles_filename = filenames["unbound_particles_filename"]
             unbound_parttypes_filename = filenames["unbound_parttypes_filename"]
 
-        number_of_particles = self.offset[halo_index + 1] - self.offset[halo_index]
-        number_of_unbound_particles = (
-            self.offset_unbound[halo_index + 1] - self.offset_unbound[halo_index]
-        )
+        if halo_index == self.offset.size - 1:  # last halo in catalog
+            with h5py.File(particles_filename) as particles_file:
+                total_particles = particles_file['Total_num_of_particles_in_all_groups'][0]
+                number_of_particles = total_particles - self.offset[halo_index]
+            with h5py.File(unbound_particles_filename) as unbound_particles_file:
+                total_unbound_particles = unbound_particles_file['Total_num_of_particles_in_all_groups'][0]
+                number_of_unbound_particles = total_unbound_particles - self.offset_unbound[halo_index]
+        else:
+            number_of_particles = self.offset[halo_index + 1] - self.offset[halo_index]
+            number_of_unbound_particles = (
+                self.offset_unbound[halo_index + 1] - self.offset_unbound[halo_index]
+            )
         assert (
             number_of_particles + number_of_unbound_particles
             == self.group_size[halo_index]
         ), "Something is incorrect in the calculation of group sizes for halo {}. Group_Size: {}, Bound: {}, Unbound: {}".format(
-            halo_index, number_of_particles, number_of_unbound_particles
+            halo_index, self.group_size[halo_index], number_of_particles, number_of_unbound_particles
         )
 
         particles = VelociraptorParticles(