Sqlalchemy CAST equivalent of Double precision
<p>i am interested to know the Sqlalchemy equivalent of the following command</p>

<p>update tablename set field1 = cast(field2 as double precision[])</p>

<p>so far, i tried the following with no luck</p>

<pre><code>from sqlalchemy import create_engine
metadata = sqlalchemy.MetaData(engine)
table = sqlalchemy.Table('tablename',md,autoload=true)
update_stmt = table.update(values={table.c.field1:cast(table.c.field2, **double precision[]**)})
engine.execute(update_stmt)
</code></pre>

<p>please help to resolve double precision equivalent in sqlalchemy. this is running update statement from python to postgresql</p>