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
```