treatment of empty spike trains in isi functions

2 files changed, 15 insertions, 2 deletions

diff --git a/pyspike/SpikeTrain.py b/pyspike/SpikeTrain.py
index a02b7ab..9127b60 100644
--- a/pyspike/SpikeTrain.py
+++ b/pyspike/SpikeTrain.py
@@ -48,3 +48,13 @@ class SpikeTrain(object):
 
         """
         return SpikeTrain(self.spikes.copy(), [self.t_start, self.t_end])
+
+    def get_spikes_non_empty(self):
+        """Returns the spikes of this spike train with auxiliary spikes in case
+        of empty spike trains.
+        """
+        if len(self.spikes) < 2:
+            return np.unique(np.insert([self.t_start, self.t_end], 1,
+                                       self.spikes))
+        else:
+            return self.spikes
diff --git a/pyspike/isi_distance.py b/pyspike/isi_distance.py
index 2a1ed3a..5ea555d 100644
--- a/pyspike/isi_distance.py
+++ b/pyspike/isi_distance.py
@@ -41,7 +41,8 @@ Falling back to slow python backend.")
         from cython.python_backend import isi_distance_python \
             as isi_profile_impl
 
-    times, values = isi_profile_impl(spike_train1.spikes, spike_train2.spikes,
+    times, values = isi_profile_impl(spike_train1.get_spikes_non_empty(),
+                                     spike_train2.get_spikes_non_empty(),
                                      spike_train1.t_start, spike_train1.t_end)
     return PieceWiseConstFunc(times, values)
 
@@ -73,7 +74,9 @@ def isi_distance(spike_train1, spike_train2, interval=None):
         try:
             from cython.cython_distances import isi_distance_cython \
                 as isi_distance_impl
-            return isi_distance_impl(spike_train1.spikes, spike_train2.spikes,
+
+            return isi_distance_impl(spike_train1.get_spikes_non_empty(),
+                                     spike_train2.get_spikes_non_empty(),
                                      spike_train1.t_start, spike_train1.t_end)
         except ImportError:
             # Cython backend not available: fall back to profile averaging