R: Install a function for conversion between user-defined units.

install_conversion_constant {units} | R Documentation

## Install a function for conversion between user-defined units.

### Description

Tells the `units` package how to convert between units that have a linear relationship, i.e. can be related on the form y = α x.

### Usage

    install_conversion_constant(from, to, const)

### Arguments

`from` | String for the symbol of the unit being converted from.
`to` | String for the symbol of the unit being converted to.
`const` | The constant α in the conversion.

### Details

This function handles the very common case where units are related through a linear function, that is, you can convert from one to the other as y = α x. Using this function, you specify that you can go from values of type `from` to values of type `to` by first multiplying a constant and then adding an offset. The function then automatically installs that conversion and the invers x = y/α.

For a more general conversion mechanism, see `install_conversion_function`.

### See Also

`install_conversion_function`

### Examples

    # one orange is worth two apples
    install_conversion_constant("orange", "apple", 2)
    apples <- 2 * as_units("apple")
    oranges <- 1 * as_units("orange")
    apples + oranges
    oranges + apples

[Package units version 0.5-1 Index]