Return ratio for conversion between units.
Returns the conversion ratio between two units, to and from, so that:
unitsratio ("meter", "centimeter")
⇒ 100
unitsratio ("inch", "foot")
⇒ 12
This allows for easy conversion between units, for example:
unitsratio ("mile", "km") * 156
⇒96.93391
For conversion between angle units, "degrees" and
"radians" are supported. For conversion between length units,
supports units defined in validateLengthUnit.
See also: units, validateLengthUnit.
Package: mapping