From a35402c208bd0ad31e5e60b6ddc55a3470e7bdde Mon Sep 17 00:00:00 2001
From: Mario Mulansky <mario.mulansky@gmx.net>
Date: Mon, 11 May 2015 17:54:02 +0200
Subject: bugfix: spike_sync=1 for empty spike trains

---
 pyspike/DiscreteFunc.py             |  4 ++--
 pyspike/cython/cython_distances.pyx |  3 ++-
 pyspike/cython/cython_profiles.pyx  | 12 ++++++++----
 pyspike/cython/python_backend.py    | 12 ++++++++----
 test/test_empty.py                  |  4 ++--
 5 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/pyspike/DiscreteFunc.py b/pyspike/DiscreteFunc.py
index 6ade87e..17153ee 100644
--- a/pyspike/DiscreteFunc.py
+++ b/pyspike/DiscreteFunc.py
@@ -137,8 +137,8 @@ class DiscreteFunc(object):
         """
 
         if len(self.y) <= 2:
-            # no actual values in the profile, return spike sync of 0
-            return 0.0, 1.0
+            # no actual values in the profile, return spike sync of 1
+            return 1.0, 1.0
 
         def get_indices(ival):
             """ Retuns the indeces surrounding the given interval"""
diff --git a/pyspike/cython/cython_distances.pyx b/pyspike/cython/cython_distances.pyx
index 16780f2..c4f2349 100644
--- a/pyspike/cython/cython_distances.pyx
+++ b/pyspike/cython/cython_distances.pyx
@@ -391,7 +391,8 @@ def coincidence_value_cython(double[:] spikes1, double[:] spikes2,
             coinc += 2
 
     if coinc == 0 and mp == 0:
-        # empty spike trains -> set mp to one to avoid 0/0
+        # empty spike trains -> spike sync = 1 by definition
+        coinc = 1
         mp = 1
 
     return coinc, mp
diff --git a/pyspike/cython/cython_profiles.pyx b/pyspike/cython/cython_profiles.pyx
index d937a02..f9893eb 100644
--- a/pyspike/cython/cython_profiles.pyx
+++ b/pyspike/cython/cython_profiles.pyx
@@ -416,9 +416,13 @@ def coincidence_profile_cython(double[:] spikes1, double[:] spikes2,
 
     st[0] = t_start
     st[len(st)-1] = t_end
-    c[0] = c[1]
-    c[len(c)-1] = c[len(c)-2]
-    mp[0] = mp[1]
-    mp[len(mp)-1] = mp[len(mp)-2]
+    if N1 + N2 > 0:
+        c[0] = c[1]
+        c[len(c)-1] = c[len(c)-2]
+        mp[0] = mp[1]
+        mp[len(mp)-1] = mp[len(mp)-2]
+    else:
+        c[0] = 1
+        c[1] = 1
 
     return st, c, mp
diff --git a/pyspike/cython/python_backend.py b/pyspike/cython/python_backend.py
index 830dc69..69a420f 100644
--- a/pyspike/cython/python_backend.py
+++ b/pyspike/cython/python_backend.py
@@ -399,10 +399,14 @@ def coincidence_python(spikes1, spikes2, t_start, t_end, max_tau):
 
     st[0] = t_start
     st[len(st)-1] = t_end
-    c[0] = c[1]
-    c[len(c)-1] = c[len(c)-2]
-    mp[0] = mp[1]
-    mp[len(mp)-1] = mp[len(mp)-2]
+    if N1 + N2 > 0:
+        c[0] = c[1]
+        c[len(c)-1] = c[len(c)-2]
+        mp[0] = mp[1]
+        mp[len(mp)-1] = mp[len(mp)-2]
+    else:
+        c[0] = 1
+        c[1] = 1
 
     return st, c, mp
 
diff --git a/test/test_empty.py b/test/test_empty.py
index b31d8a4..48be25d 100644
--- a/test/test_empty.py
+++ b/test/test_empty.py
@@ -106,11 +106,11 @@ def test_spike_sync_empty():
     st1 = SpikeTrain([], edges=(0.0, 1.0))
     st2 = SpikeTrain([], edges=(0.0, 1.0))
     d = spk.spike_sync(st1, st2)
-    assert_equal(d, 0.0)
+    assert_equal(d, 1.0)
     prof = spk.spike_sync_profile(st1, st2)
     assert_equal(d, prof.avrg())
     assert_array_equal(prof.x, [0.0, 1.0])
-    assert_array_equal(prof.y, [0.0, 0.0])
+    assert_array_equal(prof.y, [1.0, 1.0])
 
     st1 = SpikeTrain([], edges=(0.0, 1.0))
     st2 = SpikeTrain([0.4, ], edges=(0.0, 1.0))
-- 
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