[BUG] Better logic for detection of particle handle for checkpoint fi…

…les (#5019)

yt/frontends/flash/data_structures.py

@@ -1,6 +1,7 @@
 import os
 import sys
 import weakref
+from pathlib import Path
 
 import numpy as np
 
@@ -189,27 +190,38 @@ def __init__(
 
  self.particle_filename = particle_filename
 
+ filepath = Path(filename)
+
  if self.particle_filename is None:
  # try to guess the particle filename
- try:
- self._particle_handle = HDF5FileHandler(
- filename.replace("plt_cnt", "part")
- )
- self.particle_filename = filename.replace("plt_cnt", "part")
- mylog.info(
- "Particle file found: %s", self.particle_filename.split("/")[-1]
- )
- except OSError:
+ if "hdf5_plt_cnt" in filepath.name:
+ # We have a plotfile, look for the particle file
+ try:
+ pfn = str(
+ filepath.parent.resolve()
+ / filepath.name.replace("plt_cnt", "part")
+ )
+ self._particle_handle = HDF5FileHandler(pfn)
+ self.particle_filename = pfn
+ mylog.info(
+ "Particle file found: %s",
+ os.path.basename(self.particle_filename),
+ )
+ except OSError:
+ self._particle_handle = self._handle
+ elif "hdf5_chk" in filepath.name:
+ # This is a checkpoint file, should have the particles in it
  self._particle_handle = self._handle
  else:
  # particle_filename is specified by user
  self._particle_handle = HDF5FileHandler(self.particle_filename)
 
  # Check if the particle file has the same time
  if self._particle_handle != self._handle:
- part_time = self._particle_handle.handle.get("real scalars")[0][1]
- plot_time = self._handle.handle.get("real scalars")[0][1]
- if not np.isclose(part_time, plot_time):
+ plot_time = self._handle.handle.get("real scalars")
+ if (part_time := self._particle_handle.handle.get("real scalars")) is None:
+ raise RuntimeError("FLASH 2.x particle files are not supported!")
+ if not np.isclose(part_time[0][1], plot_time[0][1]):
  self._particle_handle = self._handle
  mylog.warning(
  "%s and %s are not at the same time. "