channel: fix a bug when sampling within the last element

changelog.md

@@ -8,6 +8,10 @@
   * Shortcuts `"r"`, `"g"`, and `"b"` can now be used for plotting single color channels in addition to `"red"`, `"green"`, and `"blue"`.
   * Two-channel visualizations can be plotted using `"rg"`, `"gb"`, or `"rb"`.
 
+#### Bug fixes
+
+* Fixed a bug in `downsampled_like` that would fail to indicate a lack of overlap between the low frequency and high frequency channel when sampling within the last sample of the low frequency channel.
+
 #### Improvements
 
 * Kymographs consisting of a single scan line now return a valid `line_time_seconds`. This allows certain downstream functionality, such as `Kymo.plot()`.

lumicks/pylake/channel.py

@@ -456,7 +456,7 @@ def downsampled_like(self, other_slice, reduce=np.mean):
         timestamps = other_slice.timestamps
         delta_time = np.diff(timestamps)
 
-        if self._src.start >= timestamps[-1] or self._src.stop <= timestamps[0]:
+        if self._src.start > (timestamps[-1] - delta_time[-1]) or self._src.stop <= timestamps[0]:
             raise RuntimeError("No overlap between slices.")
 
         # When the frame rate changes, one frame is very long due to the delay of the camera. It

lumicks/pylake/tests/test_channels/test_channels.py

@@ -748,11 +748,17 @@ def test_downsampling_like():
     ):
         s.downsampled_like(s)
 
-    for offset in (-4 * 4, t_downsampled[-1] + 1):
+    timestep = 4
+    for offset in (with_offset(-4 * timestep), t_downsampled[-1] - timestep + 1):
         with pytest.raises(RuntimeError, match="No overlap between slices"):
-            s = channel.Slice(channel.Continuous(np.array([1, 2, 3, 4]), with_offset(offset), 4))
+            s = channel.Slice(channel.Continuous(np.array([1, 2, 3, 4]), offset, timestep))
             s.downsampled_like(reference)
 
+    for offset in (with_offset(-4 * timestep + 1), t_downsampled[-1] - timestep):
+        print(offset - 1592916040906356300)
+        s = channel.Slice(channel.Continuous(np.array([1, 2, 3, 4]), offset, timestep))
+        s.downsampled_like(reference)
+
 
 def test_channel_plot():
     def testLine(x, y):