This app calculates the transport distance along a stream or other route. It is designed for tracking RFID tracers across multiple survey dates.

It works by assigning a location along the stream centerline for each tracer on each date. Then the distance between locations is calculated for each tracer between all dates. The scrpit relies on the sf and sfnetworks for spatial data hadnling and data.table for other data processing.

A total distance traveled is determined by selecting the maximum distance moved from all date pairs. Because a tracer may not be found in all survey dates, NA values are returned when a tracer is missing from a particular survey.

Processing times when using many files can be very slow.

Example data from surveys on Amethyst Brook, MA is provided.

Input files should be preprocessed to have a standardized tracer identification column, date column, and coordinate columns. See the example data for examples.