Fix __len__ of empty Product sweep to match actual length (#6575)

quantumlib · Apr 25, 2024 · 5828147 · 5828147
1 parent 3ff41a4
commit 5828147
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Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/cirq-core/cirq/study/sweeps.py b/cirq-core/cirq/study/sweeps.py
@@ -236,8 +236,6 @@ def keys(self) -> List['cirq.TParamKey']:
         return sum((factor.keys for factor in self.factors), [])
 
     def __len__(self) -> int:
-        if not self.factors:
-            return 0
         length = 1
         for factor in self.factors:
             length *= len(factor)

diff --git a/cirq-core/cirq/study/sweeps_test.py b/cirq-core/cirq/study/sweeps_test.py
@@ -142,6 +142,11 @@ def test_product():
     assert _values(sweep, 'b') == [4, 5, 6, 7, 4, 5, 6, 7, 4, 5, 6, 7]
 
 
+def test_empty_product():
+    sweep = cirq.Product()
+    assert len(sweep) == len(list(sweep)) == 1
+
+
 def test_slice_access_error():
     sweep = cirq.Points('a', [1, 2, 3])
     with pytest.raises(TypeError, match='<class \'str\'>'):