Rescale Aggregate id Measure to id Measure — rescale

Given a aggregate id (e.g. reachcode) measure and the from and to measure for a id (e.g. comid flowline), returns the measure along the id line. 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

Usage

rescale_measures(measure, from, to)

Arguments

measure: numeric aggregate measure between 0 and 100
from: numeric from-measure relative to the aggregate
to: numeric to-measure relative to the aggregate

Value

numeric rescaled measure

Examples

rescale_measures(40, 0, 50)
#> [1] 80
rescale_measures(60, 50, 100)
#> [1] 20