Reduced dependency on NumPy [skip ci]

Author: ankane

pgvector/pg8000/register.py

@@ -1,4 +1,3 @@
-import numpy as np
 from pg8000.native import Connection
 from .. import Vector, HalfVector, SparseVector
 
@@ -12,7 +11,11 @@ def register_vector(conn: Connection) -> None:
         raise RuntimeError('vector type not found in the database')
 
     conn.register_out_adapter(Vector, Vector._to_db)
-    conn.register_out_adapter(np.ndarray, Vector._to_db)
+    try:
+        import numpy as np
+        conn.register_out_adapter(np.ndarray, Vector._to_db)
+    except ImportError:
+        pass
     conn.register_in_adapter(type_info['vector'], Vector._from_db)
 
     if 'halfvec' in type_info:

pgvector/psycopg/vector.py

@@ -1,4 +1,3 @@
-import numpy as np
 import psycopg
 from psycopg import BaseConnection
 from psycopg.adapt import Loader, Dumper

pgvector/psycopg2/vector.py

@@ -1,4 +1,3 @@
-import numpy as np
 from psycopg2.extensions import adapt, connection, cursor, new_array_type, new_type, register_adapter, register_type
 from .. import Vector
 
@@ -23,5 +22,9 @@ def register_vector_info(oid: int, array_oid: int | None, scope: connection | cu
         vectorarray = new_array_type((array_oid,), 'VECTORARRAY', vector)
         register_type(vectorarray, scope)
 
-    register_adapter(np.ndarray, VectorAdapter)
     register_adapter(Vector, VectorAdapter)
+    try:
+        import numpy as np
+        register_adapter(np.ndarray, VectorAdapter)
+    except ImportError:
+        pass