Further improved slicing

km3io/offline.py

@@ -56,11 +56,7 @@ class cached_property:
 
 class OfflineReader:
     """reader for offline ROOT files"""
-    def __init__(self,
-                 file_path=None,
-                 fobj=None,
-                 data=None,
-                 index=slice(None)):
+    def __init__(self, file_path=None, fobj=None, data=None, index=None):
         """ OfflineReader class is an offline ROOT file wrapper
 
         Parameters
@@ -83,6 +79,7 @@ class OfflineReader:
             self._data = data
 
         for mapper in BRANCH_MAPS:
+            # print("setting mapper {}".format(mapper.name))
             setattr(self, mapper.name,
                     Branch(self._tree, mapper=mapper, index=self._index))
 
@@ -107,7 +104,7 @@ class OfflineReader:
 
     def __len__(self):
         tree = self._fobj[MAIN_TREE_NAME]
-        if self._index == slice(None):
+        if self._index is None:
             return len(tree)
         else:
             return len(
@@ -466,29 +463,37 @@ class OfflineReader:
 
 class Usr:
     """Helper class to access AAObject usr stuff"""
-    def __init__(self, name, tree, index=slice(None)):
+    def __init__(self, name, tree, index=None):
         # Here, we assume that every event has the same names in the same order
         # to massively increase the performance. This needs triple check if it's
         # always the case; the usr-format is simply a very bad design.
+        # print("initialising usr for {}".format(name))
+        # print("Setting up usr")
         self._name = name
         try:
             tree['usr']  # This will raise a KeyError in old aanet files
-                         # which has a different strucuter and key (usr_data)
-                         # We do not support those...
+            # which has a different strucuter and key (usr_data)
+            # We do not support those...
             self._usr_names = [
-                n.decode("utf-8") for n in tree['usr_names'].array()[0]
+                n.decode("utf-8") for n in tree['usr_names'].lazyarray()[0]
             ]
         except (KeyError, IndexError):  # e.g. old aanet files
             self._usr_names = []
         else:
+            # print(" checking usr data")
             self._usr_idx_lookup = {
                 name: index
                 for index, name in enumerate(self._usr_names)
             }
-            self._usr_data = tree['usr'].lazyarray(
+            data = tree['usr'].lazyarray(
                 basketcache=uproot.cache.ThreadSafeArrayCache(
-                    BASKET_CACHE_SIZE))[index]
+                    BASKET_CACHE_SIZE))
+            if index is not None:
+                data = data[index]
+            self._usr_data = data
+            # print("    adding attributes")
             for name in self._usr_names:
+                # print("  setting {}".format(name))
                 setattr(self, name, self[name])
 
     def __getitem__(self, item):
@@ -549,7 +554,7 @@ class Header:
 
 class Branch:
     """Branch accessor class"""
-    def __init__(self, tree, mapper, index=slice(None)):
+    def __init__(self, tree, mapper, index=None):
         self._tree = tree
         self._mapper = mapper
         self._index = index
@@ -606,13 +611,21 @@ class Branch:
                     })
         if isinstance(item, tuple):
             return self[item[0]][item[1]]
-        out = self._branch[self._keymap[item]].lazyarray(
-            basketcache=uproot.cache.ThreadSafeArrayCache(BASKET_CACHE_SIZE))
-        if self._index != slice(None):
-            out[self._index]
+
+        if isinstance(item, str):
+            item = self._keymap[item]
+
+            out = self._branch[item].lazyarray(
+                basketcache=uproot.cache.ThreadSafeArrayCache(
+                    BASKET_CACHE_SIZE))
+            if self._index is not None:
+                out = out[self._index]
+            return out
+
+        return self.__class__(self._tree, self._mapper, index=np.array(item))
 
     def __len__(self):
-        if self._index == slice(None):
+        if self._index is None:
             return len(self._branch)
         else:
             return len(
@@ -639,7 +652,7 @@ class BranchElement:
     index: slice
         The slice mask to be applied to the sub-arrays
     """
-    def __init__(self, name, dct, index=slice(None)):
+    def __init__(self, name, dct, index=None):
         self._dct = dct
         self._name = name
         self._index = index