Refactor offline

This refactoring includes some slicing and performance improvement attempts.

The slicing is still experimental and has some flaws:

• fancy indexing over thousands of elements might be horrible slow, eg f.events.tracks[idx_list, 0] where idx_list is a huge list of indices
• trivial problem of iterating: for track in f.evens.tracks does not stop after the last element
• meaningless indexing: f.events[5][23][420] is simply f.events[420] since the index/slice is not chained but overwritten when propagated. We need custom checks whether it makes sense
  • events are flat lists, so [x][y] does not make sense, it should throw an error
  • f.events[5:23][4] should effectively be the same as f.events[9] due to chaining of slice/index

km3io/offline.py

@@ -151,7 +151,9 @@ class Usr:
 
     def __getitem_flat__(self, item):
         if self._index_chain:
-            return _unfold_indices(self._usr_data, self._index_chain)[:, self._usr_idx_lookup[item]]
+            return _unfold_indices(
+                self._usr_data, self._index_chain)[:,
+                                                   self._usr_idx_lookup[item]]
         else:
             return self._usr_data[:, self._usr_idx_lookup[item]]
 
@@ -197,8 +199,8 @@ class OfflineReader:
     def events(self):
         """The `E` branch, containing all offline events."""
         return OfflineBranch(self._tree,
-                      mapper=EVENTS_MAP,
-                      subbranchmaps=SUBBRANCH_MAPS)
+                             mapper=EVENTS_MAP,
+                             subbranchmaps=SUBBRANCH_MAPS)
 
     @cached_property
     def header(self):