rescale_measures {hydroloom}

Rescale Aggregate id Measure to id Measure

Description

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)
rescale_measures(60, 50, 100)