Add example of setting Units.resolution in the ecephys tutorial

[h-mayorquin]

Motivation

At the inspector we are working on check_units_resolution_is_set check (NeurodataWithoutBorders/nwbinspector#685), which flags Units tables that contain spike_times but have no resolution set. Users running the inspector on files created by following our tutorials would get this warning with no guidance on how to fix it.

I have added a short section to the ecephys tutorial that sets nwbfile.units.resolution right after the existing add_unit loop, with a brief explanation of what the field means and why it matters. I kept the change minimal to avoid restructuring the existing tutorial flow.

What was the reasoning behind this change? Please explain the changes briefly.

Checklist

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.18%. Comparing base (9231882) to head (ef79487).

Additional details and impacted files

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  Coverage   95.18%   95.18%           
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  Files          30       30           
  Lines        2991     2991           
  Branches      444      444           
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  Hits         2847     2847           
  Misses         86       86           
  Partials       58       58           

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integration	73.05% <ø> (ø)
unit	85.59% <ø> (ø)

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[rly]

Suggested change

	#
	# When creating the :py:class:`~pynwb.misc.Units` table directly, you can pass it to the constructor:
	#
	# .. code-block:: python
	#
	# units = Units(name="units", resolution=1 / 30000) # 30 kHz recording system
	#
	# Since the tutorial uses :py:meth:`.NWBFile.add_unit`, we set it after the fact:

I don't think we need to show how to set it on the constructor. That is a rare edge case.

[h-mayorquin]

how is that an edge case? how are you thinking about it?

[rly]

I think most users would use nwbfile.add_unit() and nwbfile.add_unit_column() as we recommend here, rather than setting nwbfile.units = Units(name="units", ...) or creating a Units object to add elsewhere. What do you think?

[h-mayorquin]

We use the pattern in neuroconv:
https://github.com/catalystneuro/neuroconv/blob/2ddf1744208050a6229ad67d0e45f634253ae69e/src/neuroconv/tools/spikeinterface/spikeinterface.py#L2041-L2064

But yes, for the units table we don't realy use the Units constructor so it will somehow off.

I will remove it.

[h-mayorquin]

As an aside: looking at the tutorials, the constructor is used for pretty much everything (ElectricalSeries, LFP, DecompositionSeries, etc.) except the "canonical" dynamic tables on NWBFile (units, trials, epochs, electrodes, invalid_times), which always go through the add_X / add_X_column methods. The only place the gallery constructs a TimeIntervals directly is for custom (non-canonical) interval tables like sleep_stages in plot_timeintervals.py.

That convention makes sense, but I don't think it is written down anywhere, which is why "edge case" didn't immediately click for me. I remember being confused myself about how to add a constructed Units table to an NWBFile.