If this were a big deal, it could be optimized using something like a key-sharing dict implementation [1]. You can keep the dict interface to accommodate column

If this were a big deal, it could be optimized using something like a key-sharing dict implementation [1]. You can keep the dict interface to accommodate column names that aren't valid identifiers, and avoid most of the memory overhead. [1] https://www.python.org/dev/peps/pep-0412/ https://www.python.org/dev/peps/pep-0412/