Resolve "uproot4 integration"

Closes #58 (closed)

km3io/offline.py

@@ -186,8 +186,10 @@ class OfflineReader:
 
     def __getitem__(self, key):
         # indexing
-        if isinstance(key, (slice, int, np.int32, np.int64)):
-            if not isinstance(key, slice):
+        # TODO: maybe just propagate everything to awkward and let it deal
+        # with the type?
+        if isinstance(key, (slice, int, np.int32, np.int64, list, np.ndarray, ak.Array)):
+            if isinstance(key, (int, np.int32, np.int64)):
                 key = int(key)
             return self.__class__(
                 self._fobj,
@@ -296,7 +298,7 @@ class OfflineReader:
             return 1
         else:
             # ignore the usual index magic and access `id` directly
-            return len(self._fobj[self.event_path]["id"].array(), self._index_chain)
+            return len(unfold_indices(self._fobj[self.event_path]["id"].array(), self._index_chain))
 
     def __actual_len__(self):
         """The raw number of events without any indexing/slicing magic"""