Implement Identifiables support for indexing and slicing

Author: Val Brodsky

labelbox/schema/identifiables.py

@@ -12,15 +12,28 @@ def __init__(self, iterable, id_type: IdType):
             id_type: The type of id used to identify a data row.
         """
         self._iterable = iterable
-        self._index = 0
         self._id_type = id_type
 
     def __iter__(self):
         return iter(self._iterable)
 
+    def __getitem__(self, index):
+        if isinstance(index, slice):
+            ids = self._iterable[index]
+            return self.__class__(ids)  # type: ignore
+        return self._iterable[index]
+
+    def __len__(self):
+        return len(self._iterable)
+
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}({self._iterable})"
 
+    def __eq__(self, other: 'Identifiables') -> bool:
+        if not isinstance(other, Identifiables):
+            return False
+        return self._iterable == other._iterable and self._id_type == other._id_type
+
 
 class UniqueIds(Identifiables):
     """

tests/unit/test_unit_identifiables.py

@@ -6,13 +6,22 @@ def test_unique_ids():
     identifiables = UniqueIds(ids)
     assert [i for i in identifiables] == ids
     assert identifiables._id_type == "ID"
+    assert len(identifiables) == 3
 
 
 def test_global_keys():
     ids = ["a", "b", "c"]
     identifiables = GlobalKeys(ids)
     assert [i for i in identifiables] == ids
     assert identifiables._id_type == "GKEY"
+    assert len(identifiables) == 3
+
+
+def test_index_access():
+    ids = ["a", "b", "c"]
+    identifiables = GlobalKeys(ids)
+    assert identifiables[0] == "a"
+    assert identifiables[1:3] == GlobalKeys(["b", "c"])
 
 
 def test_repr():