Fixed error with empty bit strings - fixes #165

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 0.5.2 (unreleased)
 
+- Fixed error with empty `Bit` values
 - Fixed equality for `HalfVector` with signed zeros
 
 ## 0.5.1 (2026-10-08)

pgvector/bit.py

@@ -34,7 +34,11 @@ def __init__(
                 value += '0' * (8 - (length % 8))
 
             self._length = length
-            self._data = int(value, 2).to_bytes(len(value) // 8, byteorder='big')
+            # int('', 2) raises, but a zero-length bit string is valid
+            if length == 0:
+                self._data = b''
+            else:
+                self._data = int(value, 2).to_bytes(len(value) // 8, byteorder='big')
         elif is_ndarray(value):
             import numpy as np
 

tests/test_bit.py

@@ -36,6 +36,22 @@ def test_bytes(self) -> None:
         assert Bit(b'\xff\x00\xf0').to_text() == '111111110000000011110000'
         assert Bit(b'\xfe\x07\x00').to_text() == '111111100000011100000000'
 
+    def test_empty(self) -> None:
+        bit = Bit(b'')
+        assert bit.to_list() == []
+        assert bit.to_text() == ''
+        assert bit.to_binary() == pack('>i', 0)
+        assert Bit('') == bit
+        assert Bit([]) == bit
+        assert Bit.from_text('') == bit
+        assert Bit.from_text(bit.to_text()) == bit
+        assert Bit.from_binary(bit.to_binary()) == bit
+        assert bit != Bit('0')
+        assert bit != Bit(b'\x00')
+        if np is not None:
+            assert np.array_equal(bit.to_numpy(), np.array([], dtype=bool))
+            assert Bit(np.array([], dtype=bool)) == bit
+
     def test_ndarray(self) -> None:
         if np is None:
             pytest.skip('NumPy required')