round_using_magnitude {table.glue}

Set rules for rounding numbers

Description

These functions update a rounding_specification object (see round_spec) so that a particular approach to rounding is applied:

• round to a dynamic decimal place based on magnitude of the rounded number (round_using_magnitude())

• round to a specific number of significant digits (round_using_signif())

• round to a specific decimal place (round_using_decimal())

Usage

round_using_magnitude(rspec, digits = c(2, 1, 0), breaks = c(1, 10, Inf))

round_using_signif(rspec, digits = 2)

round_using_decimal(rspec, digits = 1)

Arguments

rspec

a rounding_specification object (see round_spec).

digits

for round_using_decimal() and round_using_signif, a numeric value specifying the number of decimal places and significant digits to round to, respectively. For round_using_magnitude(), digits should be a numeric vector of equal length to breaks that indicates how many decimals to round to in the numeric range designated by breaks. (see notes for example).

breaks

(only relevant if rounding based on magnitude) a positive, monotonically increasing numeric vector designating rounding boundaries.

Details

digits and breaks must be used in coordination with each other when rounding based on magnitude. For example, using breaks = c(1, 10, Inf) and decimals = c(2, 1, 0),

• numbers whose absolute value is < 1 are rounded to 2 decimal places,

• numbers whose absolute value is >= 1 and < 10 are rounding to 1 decimal place, and

• numbers whose absolute value is >= 10 are rounding to 0 decimal places. The use of magnitude to guide rounding rules is extremely flexible and can be used for many different applications (e.g., see table_pvalue). Rounding by magnitude is similar in some ways to rounding to a set number of significant digits but not entirely the same (see examples).

Value

an object of class rounding_specification.

See Also

Other rounding helpers: round_half_up()

Examples

x <- c(pi, exp(1))
x <- c(x, x*10, x*100, x*1000)

# make one specification using each rounding approach
specs <- list(
  magnitude = round_using_magnitude(round_spec()),
  decimal = round_using_decimal(round_spec()),
  signif = round_using_signif(round_spec())
)

# apply all three rounding specifications to x
# notice how the rounding specifications are in agreement
# for smaller values of x but their answers are different
# for larger values of x.

sapply(specs, function(rspec) table_value(x, rspec))

# output:
#  magnitude   decimal    signif
# [1,] "3.1"     "3.1"     "3.1"
# [2,] "2.7"     "2.7"     "2.7"
# [3,] "31"      "31.4"    "31.0"
# [4,] "27"      "27.2"    "27.0"
# [5,] "314"     "314.2"   "310.0"
# [6,] "272"     "271.8"   "270.0"
# [7,] "3,142"   "3,141.6" "3,100.0"
# [8,] "2,718"   "2,718.3" "2,700.0"