Merge pull request #1630 from OceanParcels/fix_bug_empty_pset_execute

Fixing bug when executing a breaking pset

parcels/particleset.py

@@ -840,6 +840,10 @@ def execute(self, pyfunc=AdvectionRK4, pyfunc_inter=None, endtime=None, runtime=
         delete_cfiles : bool
             Whether to delete the C-files after compilation in JIT mode (default is True)
         """
+        # check if particleset is empty. If so, return immediately
+        if len(self) == 0:
+            return
+
         # check if pyfunc has changed since last compile. If so, recompile
         if self.kernel is None or (self.kernel.pyfunc is not pyfunc and self.kernel is not pyfunc):
             # Generate and store Kernel

tests/test_particlesets.py

@@ -52,6 +52,18 @@ def test_pset_create_line(fieldset, mode, lonlatdepth_dtype, npart=100):
     assert isinstance(pset[0].lat, lonlatdepth_dtype)
 
 
+@pytest.mark.parametrize('mode', ['scipy', 'jit'])
+def test_create_empty_pset(fieldset, mode):
+    pset = ParticleSet(fieldset, pclass=ptype[mode])
+    assert pset.size == 0
+
+    def DoNothing(particle, fieldset, time):
+        pass
+
+    pset.execute(DoNothing, endtime=1., dt=1.)
+    assert pset.size == 0
+
+
 @pytest.mark.parametrize('mode', ['scipy', 'jit'])
 def test_pset_create_list_with_customvariable(fieldset, mode, npart=100):
     lon = np.linspace(0, 1, npart, dtype=np.float32)