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

@@ -214,23 +214,20 @@ class Usr:
 
 def _to_num(value):
     """Convert a value to a numerical one if possible"""
-    if value is None:
-        return
-    try:
-        return int(value)
-    except ValueError:
+    for converter in (int, float):
         try:
-            return float(value)
-        except ValueError:
+            return converter(value)
+        except (ValueError, TypeError):
             pass
-    else:
-        return value
+    return value
 
 
 class Header:
     """The header"""
     def __init__(self, header):
         self._data = {}
+        self._missing_keys = set(header.keys()) - set(mc_header.keys())
+
         for attribute, fields in mc_header.items():
             values = header.get(attribute, '').split()
             if not values:
@@ -242,13 +239,21 @@ class Header:
                 **{f: _to_num(v)
                    for (f, v) in zip(fields, values)})
 
+        # quick fix while waiting for additional definitions in mc_header
+        for key in self._missing_keys:
+            self._data[key] = _to_num(header[key])
+
         for attribute, value in self._data.items():
             setattr(self, attribute, value)
 
     def __str__(self):
         lines = ["MC Header:"]
-        for value in self._data.values():
-            lines.append("  {}".format(value))
+        keys = set(mc_header.keys())
+        for key, value in self._data.items():
+            if key in keys:
+                lines.append("  {}".format(value))
+            else:
+                lines.append("  {}: {}".format(key, value))
         return "\n".join(lines)