Add __rsub__ and values()

Author: wheerd

multiset.py

@@ -214,6 +214,11 @@ def __sub__(self, other):
             return NotImplemented
         return self.difference(other)
 
+    def __rsub__(self, other):
+        if not isinstance(other, (Set, BaseMultiset)):
+            return NotImplemented
+        return self._as_multiset(other).difference(self)
+
     def union(self, *others):
         r"""Return a new multiset with all elements from the multiset and the others with maximal multiplicities.
 
@@ -614,6 +619,8 @@ def distinct_elements(self):
     def multiplicities(self):
         return self._elements.values()
 
+    values = multiplicities
+
     @classmethod
     def _as_multiset(cls, other):
         if isinstance(other, BaseMultiset):

tests/test_multiset.py

@@ -589,6 +589,18 @@ def test_sub(MultisetCls):
     assert result is not ms
 
 
+def test_rsub(MultisetCls):
+    ms = MultisetCls('abc')
+
+    with pytest.raises(TypeError):
+        _ = 'abc' - ms
+
+    result = set('abd') - ms
+    assert sorted(result) == list('d')
+    assert isinstance(result, MultisetCls)
+    assert result is not ms
+
+
 @pytest.mark.parametrize(
     '   initial,    other,                expected',
     [
@@ -985,4 +997,14 @@ def test_str():
 def test_repr():
     ms = Multiset('aabc')
 
-    assert repr(ms) == "Multiset({'a': 2, 'b': 1, 'c': 1})"
+    assert repr(ms) == "Multiset({'a': 2, 'b': 1, 'c': 1})"
+
+
+def test_multiplicities(MultisetCls):
+    ms = MultisetCls('aaabbc')
+    assert sorted(ms.multiplicities()) == [1, 2, 3]
+
+
+def test_distinct_elements(MultisetCls):
+    ms = MultisetCls('aaabbc')
+    assert sorted(ms.distinct_elements()) == list('abc')