Rational Number Classes

Source: R/rational-class.R

An S3, S4, and R6 class for a rational number

  • rationalS3 - access fields with the '$' operator.

  • rationalS4 - access fields with the '@' operator.

  • rationalR6 - internal elements are private, so fields are accessed with accessor methods, $getNumerator(), $getDenominator(), $getValue()

The classes are designed to be used in a similar way to integers and numerics in R.

generator rational number of class rationalS3, rationalS4, and rationalR6. Each type of class has advantages and disadvantages in performance and flexibility

rational(n, d, method = "R6")

# S4 method for rationalS4
length(x)

# S3 method for rationalS3
length(x, ...)

# S3 method for rationalR6
length(x, ...)

# S4 method for rationalS4
[(x, i, j, ..., drop = TRUE)

# S4 method for rationalS4
[(x, i, j, ...) <- value

# S4 method for rationalS4
[[(x, i, ..., drop)

# S4 method for rationalS4
[[(x, i, j, ...) <- value

# S3 method for rationalS3
[(x, i, ..., drop = TRUE)

# S3 method for rationalS3
[(x, i, ...) <- value

# S3 method for rationalS3
[[(x, i, ..., exact = TRUE)

# S3 method for rationalS3
[[(x, i, ...) <- value

# S3 method for rationalR6
[(x, i, ..., drop = TRUE)

# S3 method for rationalR6
[[(x, i, ..., exact = TRUE)

# S4 method for rationalS4
print(x)

# S4 method for rationalS4
show(object)

# S3 method for rationalS3
print(x, ...)

# S3 method for rationalR6
print(x, ...)

Arguments

n

the numerator
d

the denominator
method

a length = 1 character vector. One of "R6" (default), "S3", "S4"
x

the rational number
...

indices specifying elements to extract or replace. Indices are numeric or character vectors or empty (missing) or NULL.
i

index specifying elements
j

index specifying elements
drop

For matrices and arrays. If TRUE the result is coerced to the lowest possible dimension (see the examples). This only works for extracting elements, not for the replacement. See drop for further details.
value

the replacement value
exact

controls partial matching when extracting by character
object

the object to show

Value

the desired instance of the rational class

Fields

n,d,v

the numerator, denominator, and value field of the S3 class

Slots

n

the numerator of the S4 class

d

the denominator of the S4 class

v

the numeric value of the S4 class

Note

note that Inf, NA, NaN, and NULL all fail on is.integer() and are not permitted

See also

Extract for more full descriptions

Examples

 a <- rational(1L, 3L, method="S3")
 stopifnot(a$n == 1L && a$d == 3L && abs(a$v - 1/3) < 1E-12)
 stopifnot(class(a) == "rationalS3")
 b <- rational(2L, 5L, method="S4")
 stopifnot(b@n == 2L && b@d == 5L && abs(b@v - 2/5) < 1E-12)
 stopifnot(class(b) == "rationalS4" && isS4(b) && is(b, "rationalS4"))
 d <- rational(3L, 7L, method="R6")
 stopifnot(d$getNumerator() == 3L && d$getDenominator() == 7L && abs(d$getValue() - 3/7) < 1E-12)
 stopifnot(class(d)[1] == "rationalR6" && is(d, "rationalR6") && is(d, "R6"))
  a <- rational(c(3L, 5L, 6L), c(4L, 5L, 7L), "S4")
  stopifnot(length(a) == 3)
  a <- rational(c(3L, 5L, 6L), c(4L, 5L, 7L), "S3")
  stopifnot(length(a) == 3)
  a <- rational(c(3L, 5L, 6L), c(4L, 5L, 7L), "R6")
  stopifnot(length(a) == 3)
  a <- rational(c(3L, 5L, 6L), c(4L, 5L, 7L), "S4")
  stopifnot(a[2]@n == 5L)
  stopifnot(all(a[2:3]@n == c(5,6)))
  a <- rational(c(3L, 5L, 6L), c(4L, 5L, 7L), "S3")
  stopifnot(a[2]$n == 5L)
  stopifnot(all(a[2:3]$n == c(5,6)))
  a <- rational(c(3L, 5L, 6L), c(4L, 5L, 7L), "R6")
  stopifnot(a[2]$getNumerator() == 5L)
  stopifnot(all(a[2:3]$n == c(5,6)))