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Uncommon rounding procedures

Source: R/round-ceil-floor.R
rounding-uncommon.Rd

Always round up, down, toward zero, or away from it:

  • round_ceiling() always rounds up.

  • round_floor() always rounds down.

  • round_trunc() always rounds toward zero.

  • round_anti_trunc() always rounds away from zero. (0 itself is rounded to 1.)

  • anti_trunc() does not round but otherwise works like round_anti_trunc().

Despite not being widely used, they are featured here in case they are needed for reconstruction.

Usage

round_ceiling(x, digits = 0L)

round_floor(x, digits = 0L)

round_trunc(x, digits = 0L)

anti_trunc(x)

round_anti_trunc(x, digits = 0L)

Arguments

x

Numeric. The decimal number to round.

digits

Integer. Number of digits to round x to. Default is 0.

Value

Numeric. x rounded to digits (except for anti_trunc(), which has no digits argument).

Details

round_ceiling(), round_floor(), and round_trunc() generalize the base R functions ceiling(), floor(), and trunc(), and include them as special cases: With the default value for digits, 0, these round_* functions are equivalent to their respective base counterparts.

The last round_* function, round_anti_trunc(), generalizes another function presented here: anti_trunc() works like trunc() except it moves away from 0, rather than towards it. That is, whereas trunc() minimizes the absolute value of x (as compared to the other rounding functions), anti_trunc() maximizes it. anti_trunc(x) is therefore equal to trunc(x) + 1 if x is positive, and to trunc(x) - 1 if x is negative.

round_anti_trunc(), then, generalizes anti_trunc() just as round_ceiling() generalizes ceiling(), etc.

Moreover, round_trunc() is equivalent to round_floor() for positive numbers and to round_ceiling() for negative numbers. The reverse is again true for round_anti_trunc(): It is equivalent to round_ceiling() for positive numbers and to round_floor() for negative numbers.

See also

round_up() and round_down() round up or down from 5, respectively. round_up_from() and round_down_from() allow users to specify custom thresholds for rounding up or down.

Examples

# Always round up:
round_ceiling(x = 4.52, digits = 1)        # 2 cut off
#> [1] 4.6

# Always round down:
round_floor(x = 4.67, digits = 1)          # 7 cut off
#> [1] 4.6

# Always round toward 0:
round_trunc(8.439, digits = 2)             # 9 cut off
#> [1] 8.43
round_trunc(-8.439, digits = 2)            # 9 cut off
#> [1] -8.43

# Always round away from 0:
round_anti_trunc(x = 8.421, digits = 2)    # 1 cut off
#> [1] 8.43
round_anti_trunc(x = -8.421, digits = 2)   # 1 cut off
#> [1] -8.43