Use numpy typing

yt/frontends/rockstar/data_structures.py

@@ -4,6 +4,7 @@
 from typing import List, Optional
 
 import numpy as np
+from numpy import typing as npt
 
 from yt.data_objects.static_output import ParticleDataset
 from yt.frontends.halo_catalog.data_structures import HaloCatalogFile
@@ -20,7 +21,7 @@ class RockstarBinaryFile(HaloCatalogFile):
     header: dict
     _position_offset: int
     _member_offset: int
-    _Npart: np.array
+    _Npart: npt.NDArray[np.int64]
     _ids_halos: List[int]
     _file_size: int
 
@@ -46,7 +47,7 @@ def __init__(self, ds, io, filename, file_id, range):
 
         super().__init__(ds, io, filename, file_id, range)
 
-    def _read_member(self, ihalo: int) -> Optional[np.array]:
+    def _read_member(self, ihalo: int) -> Optional[npt.NDArray[np.int64]]:
         if ihalo not in self._ids_halos:
             return None
 
@@ -59,7 +60,7 @@ def _read_member(self, ihalo: int) -> Optional[np.array]:
             ids = np.fromfile(f, dtype=np.int64, count=self._Npart[ind_halo])
             return ids
 
-    def _read_particle_positions(self, ptype, f=None):
+    def _read_particle_positions(self, ptype: str, f=None):
         """
         Read all particle positions in this file.
         """