Always segment at non-monotonic timestamps in _jitter_removal

* Segment when timestamp intervals exceed threshold (previous
  behaviour)

* Always segment at non-positive timestamp intervals (irrespective of
  threshold)

* Additional tests for non-monotonicity

src/pyxdf/pyxdf.py

@@ -629,9 +629,9 @@ def _detect_breaks(stream, threshold_seconds=1.0, threshold_samples=500):
     """Detect breaks in the time_stamps of a stream."""
     # Identify breaks in the time_stamps
     diffs = np.diff(stream.time_stamps)
-    b_breaks = np.abs(diffs) > np.max(
+    b_breaks = (diffs <= 0) | (diffs > np.max(
         (threshold_seconds, threshold_samples * stream.tdiff)
-    )
+    ))
     # find indices (+ 1 to compensate for lost sample in np.diff)
     break_inds = np.where(b_breaks)[0] + 1
     return break_inds

test/test_jitter_removal.py

@@ -1,4 +1,3 @@
-import pytest
 from pyxdf.pyxdf import _detect_breaks
 
 
@@ -8,44 +7,105 @@ def __init__(self, time_stamps, tdiff):
         self.tdiff = tdiff
 
 
-def test_detect_no_breaks():
+def test_detect_no_breaks_seconds():
     timestamps = list(range(-5, 5))
     stream = MockStreamData(timestamps, 1)
-    # if diff > 2 and larger 500 * tdiff -> 0
-    breaks = _detect_breaks(stream, threshold_seconds=2, threshold_samples=500)
+    # if diff > 2 and larger 0 * tdiff -> 0
+    breaks = _detect_breaks(stream, threshold_seconds=2, threshold_samples=0)
     assert breaks.size == 0
-    # if diff > 0.1 and larger 1 * tdiff -> 0
-    breaks = _detect_breaks(stream, threshold_seconds=0.1, threshold_samples=1)
+    # if diff > 1 and larger 0 * tdiff -> 0
+    breaks = _detect_breaks(stream, threshold_seconds=1, threshold_samples=0)
     assert breaks.size == 0
 
 
-def test_detect_breaks_reverse():
-    timestamps = list(reversed(range(-5, 5)))
+def test_detect_no_breaks_samples():
+    timestamps = list(range(-5, 5))
+    stream = MockStreamData(timestamps, 1)
+    # if diff > 0 and larger 2 * tdiff -> 0
+    breaks = _detect_breaks(stream, threshold_seconds=0, threshold_samples=2)
+    assert breaks.size == 0
+    # if diff > 0 and larger 1 * tdiff -> 0
+    breaks = _detect_breaks(stream, threshold_seconds=0, threshold_samples=1)
+    assert breaks.size == 0
+
+
+def test_detect_breaks_seconds():
+    timestamps = list(range(-5, 5, 2))
     stream = MockStreamData(timestamps, 1)
+    # if diff > 1 and larger 0 * tdiff -> 4
     breaks = _detect_breaks(stream, threshold_seconds=0.1, threshold_samples=0)
     assert breaks.size == len(timestamps) - 1
 
 
+def test_detect_breaks_samples():
+    timestamps = list(range(-5, 5, 2))
+    stream = MockStreamData(timestamps, 1)
+    # if diff > 0 and larger 1 * tdiff -> 4
+    breaks = _detect_breaks(stream, threshold_seconds=0, threshold_samples=1)
+    assert breaks.size == len(timestamps) - 1
+
+
 def test_detect_breaks_gap_in_negative():
     timestamps = [-4, 1, 2, 3, 4]
     stream = MockStreamData(timestamps, 1)
+    # if diff > 1 and larger 1 * tdiff -> 1
     breaks = _detect_breaks(stream, threshold_seconds=1, threshold_samples=1)
     assert breaks.size == 1
     assert breaks[0] == 1
     timestamps = [-4, -2, -1, 0, 1, 2, 3, 4]
     stream = MockStreamData(timestamps, 1)
+    # if diff > 1 and larger 1 * tdiff -> 1
     breaks = _detect_breaks(stream, threshold_seconds=1, threshold_samples=1)
     assert breaks.size == 1
     assert breaks[0] == 1
+    # if diff > 0.1 and larger 0 * tdiff -> 7
+    breaks = _detect_breaks(stream, threshold_seconds=0.1, threshold_samples=0)
+    assert breaks.size == len(timestamps) - 1
 
 
 def test_detect_breaks_gap_in_positive():
     timestamps = [1, 3, 4, 5, 6]
     stream = MockStreamData(timestamps, 1)
-    # if diff > 1 and larger 1 * tdiff -> 1 -> 1
+    # if diff > 1 and larger 1 * tdiff -> 1
     breaks = _detect_breaks(stream, threshold_seconds=1, threshold_samples=1)
     assert breaks.size == 1
     assert breaks[0] == 1
-    # if diff > 0.1 and larger 0 * tdiff ->
+    # if diff > 0.1 and larger 0 * tdiff -> 4
+    breaks = _detect_breaks(stream, threshold_seconds=0.1, threshold_samples=0)
+    assert breaks.size == len(timestamps) - 1
+
+
+def test_detect_breaks_reverse():
+    timestamps = list(reversed(range(-5, 5)))
+    stream = MockStreamData(timestamps, 1)
+    # if diff <= 0 -> 9
+    breaks = _detect_breaks(stream, threshold_seconds=0, threshold_samples=0)
+    assert breaks.size == len(timestamps) - 1
+
+
+def test_detect_breaks_gaps_non_monotonic():
+    timestamps = [-4, 1, -3, -2, -1, 1, 5, 1, 2]
+    stream = MockStreamData(timestamps, 1)
+    # if diff <= 0 or diff > 1 and larger 1 * tdiff -> 5
+    breaks = _detect_breaks(stream, threshold_seconds=1, threshold_samples=1)
+    assert list(breaks) == [1, 2, 5, 6, 7]
+    # if diff <= 0 or diff > 2 and larger 1 * tdiff -> 4
+    breaks = _detect_breaks(stream, threshold_seconds=2, threshold_samples=1)
+    assert list(breaks) == [1, 2, 6, 7]
+    # if diff <= 0 or diff > 0.1 and larger 0 * tdiff -> 8
+    breaks = _detect_breaks(stream, threshold_seconds=0.1, threshold_samples=0)
+    assert breaks.size == len(timestamps) - 1
+
+
+def test_detect_breaks_strict_non_monotonic():
+    timestamps = [-4, -5, -3, -2, -1, 0, 0, 1, 2]
+    stream = MockStreamData(timestamps, 1)
+    # if diff <= 0 or diff > 1 and larger 1 * tdiff -> 3
+    breaks = _detect_breaks(stream, threshold_seconds=1, threshold_samples=1)
+    assert list(breaks) == [1, 2, 6]
+    # if diff <= 0 or diff > 2 and larger 2 * tdiff -> 2
+    breaks = _detect_breaks(stream, threshold_seconds=2, threshold_samples=2)
+    assert list(breaks) == [1, 6]
+    # if diff <= 0 or diff > 0.1 and larger 0 * tdiff -> 8
     breaks = _detect_breaks(stream, threshold_seconds=0.1, threshold_samples=0)
     assert breaks.size == len(timestamps) - 1