Given a reachcode measure and the from and to measure for a comid flowline, returns the measure along the comid flowline. This is a utility specific to the NHDPlus data model where many comid flowlines make up a single reachcode / reach. "Measures" are typically referenced to reaches. Flowlines have a stated from-measure / to-measure. In some cases it is useful to rescale the measure such that it is relative only to the flowline.
from is downstream -- 0 is the outlet to is upstream -- 100 is the inlet
rescale_measures(measure, from, to)
numeric reach measure between 0 and 100
numeric flowline from-measure relative to the reach
numeric flowline to-measure relative to the reach
numeric rescaled measure
rescale_measures(40, 0, 50) #>  80 rescale_measures(60, 50, 100) #>  20