electrodes column in misc.Units.add_unit() doesn't adhere to nwb-schema

[bjhardcastle]

If I'm looking at the right thing, then the schema specifies the column as a DynamicTableRegion and the column in the units table should be a link to the electrodes table:
https://github.com/NeurodataWithoutBorders/nwb-schema/blob/dev/core/nwb.misc.yaml#L219-L222

  - name: electrodes
    neurodata_type_inc: DynamicTableRegion
    doc: Electrode that each spike unit came from, specified using a DynamicTableRegion.
    quantity: '?'

...which doesn't match the accepted types in add_unit():

pynwb/src/pynwb/misc.py

Lines 189 to 190 in eb58506

	{'name': 'electrodes', 'type': 'array_data', 'doc': 'the electrodes that each unit came from',
	'default': None},

..and just to check that DynamicTableRegion isn't an 'array_data' type:

Units.add_unit: incorrect type for 'electrodes' (got 'DynamicTableRegion', expected 'ndarray, list, tuple, Dataset, Array, StrDataset, HDMFDataset or AbstractDataChunkIterator')

Presumably this is expecting a sequence of integers, which are the indices of the corresponding rows in the electrodes table, but it's not clear: the description sounds more like links to the electrodes table.

[bjhardcastle]

Ok I see what's going on now: you pass a sequence of integers and the DynamicTableRegion is magically created for you!

It just looks like the sequence of integers when viewed as a pandas series:

>>> units['electrodes'][0]
   location                                              group  ... reference       imp
id                                                              ...                    
0       Eth  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
1       Eth  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
2       Eth  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
3        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
4        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
5        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
6        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
7        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
8        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0
9        LP  probeA pynwb.ecephys.ElectrodeGroup at 0x30363...  ...       tip  150000.0

[10 rows x 12 columns]

>>> units[0].electrodes
id
1    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Name: electrodes, dtype: object

The description could still be more helpful though.