install_conversion_constant {units} | R Documentation |
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.
install_conversion_constant(from, to, const)
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. |
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
.
apples <- 2 * make_unit("apple") oranges <- 1 * make_unit("orange") # one orange is worth two apples install_conversion_constant("orange", "apple", 2) apples + oranges oranges + apples