I'm building a consolidated map of all transit systems in my area in QGIS. I have a GTFS dataset of bus lines, and it includes shapes for every trip on every route in the system (as it should), but that's far more detail than I need, and very slow to render.
I'd like to filter the data to map only the longest possible trip on each route in each direction (inbound/outbound). What's the best way to do this? Line number, route direction, and shape length are all separate columns. I'd prefer to keep the underlying dataset intact if possible.