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

@@ -189,7 +189,7 @@ class Header:
     """The header"""
     def __init__(self, header):
         self._data = {}
-        self._missing_keys = list(set(header.keys()) - set(mc_header.keys()))
+        self._missing_keys = set(header.keys()) - set(mc_header.keys())
 
         for attribute, fields in mc_header.items():
             values = header.get(attribute, '').split()