Merge branch 'master' of github.com:dgilland/pydash

pydash/collections.py

@@ -141,18 +141,32 @@ def for_each_right(*args, **kargs):  # pragma: no cover
 each_right = for_each_right
 
 
-def group_by(*args, **kargs):  # pragma: no cover
+def group_by(collection, callback):
     """Creates an object composed of keys generated from the results of running
     each element of a `collection` through the callback.
     """
-    raise NotImplementedError
+    ret = dict()
+    cb = _make_callback(callback)
+
+    for value in collection:
+        key = cb(value)
+        ret.setdefault(key, [])
+        ret[key].append(value)
+
+    return ret
 
 
-def index_by(*args, **kargs):  # pragma: no cover
+def index_by(collection, callback):
     """Creates an object composed of keys generated from the results of running
     each element of the collection through the given callback.
     """
-    raise NotImplementedError
+    ret = dict()
+    cb = _make_callback(callback)
+
+    for value in collection:
+        ret[cb(value)] = value
+
+    return ret
 
 
 def invoke(*args, **kargs):  # pragma: no cover

tests/test_pydash.py

@@ -442,6 +442,23 @@ def test_find_last(case, expected):
     assert pyd.find_last(*case) == expected
 
 
+@parametrize('case,expected', [
+    (([4.2, 6.1, 6.4],
+      lambda num, *args: int(math.floor(num))),
+     {4: [4.2], 6: [6.1, 6.4]}),
+])
+def test_group_by(case, expected):
+    assert pyd.group_by(*case) == expected
+
+
+@parametrize('case,expected', [
+    (([{'dir': 'left', 'code': 97}, {'dir': 'right', 'code': 100}], 'dir'),
+     {'left': {'dir': 'left', 'code': 97}, 'right': {'dir': 'right', 'code': 100}}),
+])
+def test_index_by(case, expected):
+    assert pyd.index_by(*case) == expected
+
+
 @parametrize('case', [
     fixtures.data.sample,
 ])