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Generalized rounding to the nearest fraction of a specified denominator

Source: R/reround-to-fraction.R
fractional-rounding.Rd

Two functions that round numbers to specific fractions, not just to the next higher decimal level. They are inspired by janitor::round_to_fraction() but feature all the options of reround():

  • reround_to_fraction() closely follows janitor::round_to_fraction() by first rounding to fractions of a whole number, then optionally rounding the result to a specific number of digits in the usual way.

  • reround_to_fraction_level() rounds to the nearest fraction of a number at the specific decimal level (i.e., number of digits), without subsequent rounding. This is closer to conventional rounding functions.

Usage

reround_to_fraction(
  x = NULL,
  denominator = 1,
  digits = Inf,
  rounding = "up_or_down",
  threshold = 5,
  symmetric = FALSE
)

reround_to_fraction_level(
  x = NULL,
  denominator = 1,
  digits = 0L,
  rounding = "up_or_down",
  threshold = 5,
  symmetric = FALSE
)

Arguments

x

Numeric. Vector of numbers to be rounded.

denominator

Numeric (>= 1) . x will be rounded to the nearest fraction of denominator. Default is 1.

digits

Numeric (whole numbers).

  • In reround_to_fraction(): If digits is specified, the values resulting from fractional rounding will subsequently be rounded to that many decimal places. If set to "auto", it internally becomes ceiling(log10(denominator)) + 1, as in janitor::round_to_fraction(). Default is Inf, in which case there is no subsequent rounding.

  • In reround_to_fraction_level(): This function will round to a fraction of the number at the decimal level specified by digits. Default is 0.

rounding, threshold, symmetric

More arguments passed down to reround().

Value

Numeric vector of the same length as x unless rounding is either of "up_or_down", "up_from_or_down_from", and "ceiling_or_floor". In these cases, it will always have length 2.

See also

reround(), which the functions wrap, and janitor::round_to_fraction(), part of which they copy.

Examples

#`reround_to_fraction()` rounds `0.4`
# to `0` if `denominator` is `1`, which
# is the usual integer rounding...
reround_to_fraction(0.4, denominator = 1, rounding = "even")
#> [1] 0

# ...but if `denominator` is `2`, it rounds to the nearest
# fraction of 2, which is `0.5`:
reround_to_fraction(0.4, denominator = 2, rounding = "even")
#> [1] 0.5

# Likewise with fractions of 3:
reround_to_fraction(0.25, denominator = 3, rounding = "even")
#> [1] 0.3333333

# The default for `rounding` is to round
# both up and down, as in `reround()`:
reround_to_fraction(0.4, denominator = 2)
#> [1] 0.5 0.5

# These two rounding procedures differ
# at the tie points:
reround_to_fraction(0.25, denominator = 2)
#> [1] 0.5 0.0

# `reround_to_fraction_level()`, in contrast,
# uses `digits` to determine some decimal level,
# and then rounds to the closest fraction at
# that level:
reround_to_fraction_level(0.12345, denominator = 2, digits = 0)
#> [1] 0 0
reround_to_fraction_level(0.12345, denominator = 2, digits = 1)
#> [1] 0.1 0.1
reround_to_fraction_level(0.12345, denominator = 2, digits = 2)
#> [1] 0.125 0.125