channel loader returns the electrode sites indexing, closes #893 (#894)

Author: oliche

brainbox/io/one.py

@@ -1017,7 +1017,10 @@ def load_channels(self, **kwargs):
         self.download_spike_sorting_object(obj='channels', missing='ignore', **kwargs)
         channels = self._load_object(self.files['channels'], wildcards=self.one.wildcards)
         if 'electrodeSites' in self.files:  # if common dict keys, electrodeSites prevails
-            channels = channels | self._load_object(self.files['electrodeSites'], wildcards=self.one.wildcards)
+            esites = channels | self._load_object(self.files['electrodeSites'], wildcards=self.one.wildcards)
+            if alfio.check_dimensions(esites) != 0:
+                esites = self._load_object(self.files['electrodeSites'], wildcards=self.one.wildcards)
+                esites['rawInd'] = np.arange(esites[list(esites.keys())[0]].shape[0])
         if 'brainLocationIds_ccf_2017' not in channels:
             _logger.debug(f"loading channels from alyx for {self.files['channels']}")
             _channels, self.histology = _load_channel_locations_traj(