First iteration prototype

km3io/offline.py

@@ -19,8 +19,8 @@ class OfflineReader(EventReader):
     item_name = "OfflineEvent"
     skip_keys = ["t", "AAObject"]
     aliases = {
-        "t_sec": "t.fSec",
-        "t_ns": "t.fNanoSec",
+        "t_sec": "t/t.fSec",
+        "t_ns": "t/t.fNanoSec",
         "usr": "AAObject/usr",
         "usr_names": "AAObject/usr_names",
     }

km3io/rootio.py

@@ -95,13 +95,28 @@ class EventReader:
 
     def _initialise_keys(self):
         skip_keys = set(self.skip_keys)
-        toplevel_keys = set(k.split("/")[0] for k in self._fobj[self.event_path].keys())
+        all_keys  = set(self._fobj[self.event_path].keys())
+        toplevel_keys = set(k.split("/")[0] for k in all_keys)
+        valid_aliases = {}
+        for fromkey, tokey in self.aliases.items():
+            if tokey in all_keys:
+                valid_aliases[fromkey] = tokey
+        self.aliases = valid_aliases
         keys = (toplevel_keys - skip_keys).union(
-            list(self.aliases.keys()) + list(self.nested_aliases)
+            list(valid_aliases) + list(self.nested_aliases)
         )
         for key in list(self.nested_branches) + list(self.nested_aliases):
             keys.add("n_" + key)
         # self._grouped_branches = {k for k in toplevel_keys - skip_keys if isinstance(self._fobj[self.event_path][k].interpretation, uproot.AsGrouped)}
+        valid_nested_branches = {}
+        for nested_key, aliases in self.nested_branches.items():
+            if nested_key in toplevel_keys:
+                valid_nested_branches[nested_key] = {}
+                subbranch_keys = self._fobj[self.event_path][nested_key].keys()
+                for fromkey, tokey in aliases.items():
+                    if tokey in subbranch_keys:
+                        valid_nested_branches[nested_key][fromkey] = tokey
+        self.nested_branches = valid_nested_branches
         self._keys = keys
 
     def keys(self):
@@ -187,7 +202,6 @@ class EventReader:
         )  # all top-level keys for regular branches
         log.debug("keys: %s", keys)
         log.debug("aliases: %s", self.aliases)
-        # check for valid keys, e.g. `usr` is not always there and raises recursion error!
         events_it = events.iterate(
             keys, aliases=self.aliases, step_size=self._step_size
         )
@@ -197,8 +211,6 @@ class EventReader:
         )  # dict-key ordering is an implementation detail
         log.debug("nested_keys: %s", nested_keys)
         for key in nested_keys:
-            # print(f"adding {key} with keys {self.nested_branches[key].keys()} and aliases {self.nested_branches[key]}")
-
             nested.append(
                 events[key].iterate(
                     self.nested_branches[key].keys(),

km3io/tools.py

@@ -264,7 +264,10 @@ def best_track(tracks, startend=None, minmax=None, stages=None):
     if minmax is not None:
         m1 = mask(tracks.rec_stages, minmax=minmax)
 
-    original_ndim = tracks.ndim
+    try:
+        original_ndim = tracks.ndim
+    except AttributeError:
+        original_ndim = 1
     axis = 1 if original_ndim == 2 else 0
 
     tracks = tracks[m1]
@@ -278,6 +281,8 @@ def best_track(tracks, startend=None, minmax=None, stages=None):
 
     out = tracks[m3]
     if original_ndim == 1:
+        if isinstance(out, ak.Record):
+            return out[:, 0]
         return out[0]
     return out[:, 0]