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%as% is a binary operator on strings with units in them

grapes-as-grapes.Rd

The function calls the units utility and converts the string on the left into the unit on the right, e.g.: "cm" %as% "inches", both units can contain numbers. Any input that is accepted by the units utility is acceptable, as long as it makes sense with the command line arguments: units --strict --compact -1 "$originalUnit" "$targetUnit"

Usage

txtUnit %as% target

Arguments

txtUnit

a string with numeric values, including units, e.g. "3 cm", can be a character vector

target

string, target unit, e.g. "m", must be scalar

Value

a numeric value y: valoriginalUnit = ytargetUnit, the target unit is attached to the returned value, as a comment.

Examples

  ## needs `unit` utility (a system utility)
  if (nzchar(Sys.which("units"))){
    y <- "21 cm" %as% "inches"
    y <- "12 nmol/L" %as% "mol/L"
    print(comment(y))
    y <- "12 mol/m^3" %as% "mmol/L"
  } else {
    message("The system utility 'units' is not installed, skipping example.")
  }
#> Warning: The 'units' utility must be installed (system program, not R).
#> Warning: The 'units' utility must be installed (system program, not R).
#> NULL
#> Warning: The 'units' utility must be installed (system program, not R).