gdpyc estimates Galactic hydrogen column densities, extinction, and reddening along arbitrary lines of sight. The package wraps HEALPix all-sky gas and dust maps, downloading and processing them as needed to provide map-based queries for individual sky coordinates or source lists. gdpyc offers functionality similar to commonly used nh tools, exposing both command-line and Python interfaces for integrating column-density and extinction estimates into analysis workflows.