Fix variable typo; add docstring

src/spikeinterface/sortingcomponents/motion/motion_interpolation.py

@@ -3,7 +3,8 @@
 import numpy as np
 from spikeinterface.core.core_tools import define_function_from_class
 from spikeinterface.preprocessing import get_spatial_interpolation_kernel
-from spikeinterface.preprocessing.basepreprocessor import BasePreprocessor, BasePreprocessorSegment
+from spikeinterface.preprocessing.basepreprocessor import (
+    BasePreprocessor, BasePreprocessorSegment)
 from spikeinterface.preprocessing.filter import fix_dtype
 
 from .motion_utils import ensure_time_bin_edges, ensure_time_bins
@@ -155,7 +156,7 @@ def interpolate_motion_on_traces(
     interp_times = np.empty(total_num_chans)
     current_start_index = 0
     for interp_bin_ind in interpolation_bins_here:
-        bin_time = bin_centers_s[interp_bin_ind]
+        bin_time = interpolation_time_bin_centers_s[interp_bin_ind]
         interp_times.fill(bin_time)
         channel_motions = motion.get_displacement_at_time_and_depth(
             interp_times,

src/spikeinterface/sortingcomponents/motion/motion_utils.py

@@ -580,6 +580,22 @@ def make_3d_motion_histograms(
 
 
 def ensure_time_bins(time_bin_centers_s=None, time_bin_edges_s=None):
+    """Ensure that both bin edges and bin centers are present
+
+    If either of the inputs are None but not both, the missing is reconstructed
+    from the present. Going from edges to centers is done by taking midpoints.
+    Going from centers to edges is done by taking midpoints and padding with the
+    left and rightmost centers.
+
+    Parameters
+    ----------
+    time_bin_centers_s : None or np.array
+    time_bin_edges_s : None or np.array
+
+    Returns
+    -------
+    time_bin_centers_s, time_bin_edges_s
+    """
     if time_bin_centers_s is None and time_bin_edges_s is None:
         raise ValueError("Need at least one of time_bin_centers_s or time_bin_edges_s.")