Also supporting outputdt as float

Author: erikvansebille

src/parcels/_core/particlefile.py

@@ -52,7 +52,7 @@ class ParticleFile:
     outputdt :
         Interval which dictates the update frequency of file output
         while ParticleFile is given as an argument of ParticleSet.execute()
-        It is either a timedelta object or a positive double.
+        It is either a numpy.timedelta64, a datimetime.timedelta object or a positive float (in seconds).
     chunks :
         Tuple (trajs, obs) to control the size of chunks in the zarr output.
     create_new_zarrfile : bool
@@ -65,14 +65,15 @@ class ParticleFile:
     """
 
     def __init__(self, store, outputdt, chunks=None, create_new_zarrfile=True):
-        if isinstance(outputdt, timedelta):
-            outputdt = np.timedelta64(int(outputdt.total_seconds()), "s")
+        if not isinstance(outputdt, (np.timedelta64, timedelta, float)):
+            raise ValueError(
+                f"Expected outputdt to be a np.timedelta64, datetime.timedelta or float (in seconds), got {type(outputdt)}"
+            )
 
-        if not isinstance(outputdt, np.timedelta64):
-            raise ValueError(f"Expected outputdt to be a np.timedelta64 or datetime.timedelta, got {type(outputdt)}")
+        outputdt = timedelta_to_float(outputdt)
 
-        if outputdt <= np.timedelta64(0, "s"):
-            raise ValueError(f"outputdt must be a positive non-zero timedelta. Got {outputdt=!r}")
+        if outputdt <= 0:
+            raise ValueError(f"outputdt must be positive/non-zero. Got {outputdt=!r}")
 
         self._outputdt = outputdt
 

src/parcels/_core/particleset.py

@@ -492,7 +492,7 @@ def execute(
         if np.isnan(self._data["time"]).any():
             self._data["time"][:] = start_time
 
-        outputdt = timedelta_to_float(output_file.outputdt) if output_file else None
+        outputdt = output_file.outputdt if output_file else None
         _warn_outputdt_release_desync(outputdt, start_time, self._data["time"][:])
 
         # Set up pbar

tests/test_particlefile.py

@@ -1,6 +1,7 @@
 import os
 import tempfile
-from datetime import timedelta
+from contextlib import nullcontext as does_not_raise
+from datetime import datetime, timedelta
 
 import numpy as np
 import pytest
@@ -231,6 +232,23 @@ def test_file_warnings(fieldset, tmp_zarrfile):
         pset.execute(AdvectionRK4, runtime=3, dt=1, output_file=pfile)
 
 
+@pytest.mark.parametrize(
+    "outputdt, expectation",
+    [
+        (np.timedelta64(5, "s"), does_not_raise()),
+        (timedelta(seconds=2), does_not_raise()),
+        (5.0, does_not_raise()),
+        (np.datetime64("2001-01-02T00:00:00"), pytest.raises(ValueError)),
+        (datetime(2000, 1, 2, 0, 0, 0), pytest.raises(ValueError)),
+        (-np.timedelta64(5, "s"), pytest.raises(ValueError)),
+    ],
+)
+def test_outputdt_types(outputdt, expectation, tmp_zarrfile):
+    with expectation:
+        pfile = ParticleFile(tmp_zarrfile, outputdt=outputdt)
+        assert pfile.outputdt == timedelta_to_float(outputdt)
+
+
 def test_write_timebackward(fieldset, tmp_zarrfile):
     release_time = fieldset.time_interval.left + [np.timedelta64(i + 1, "s") for i in range(3)]
     pset = ParticleSet(fieldset, lat=[0, 1, 2], lon=[0, 0, 0], time=release_time)