Round values while preserve their rounded sum in R

Sometimes, the sum of rounded numbers (e.g., using base::round()) is not the same as their rounded sum.

Usage

round_preserve_sum(x, digits = 0)

Source

https://biostatmatt.com/archives/2902

Arguments

x

Numerical vector to sum.

digits

Number of decimals for rounding.

Value

A numerical vector of same length as x.

Details

This solution applies the following algorithm

• Round down to the specified number of decimal places

• Order numbers by their remainder values

• Increment the specified decimal place of values with k largest remainders, where k is the number of values that must be incremented to preserve their rounded sum

Examples

sum(c(0.333, 0.333, 0.334))
#> [1] 1
round(c(0.333, 0.333, 0.334), 2)
#> [1] 0.33 0.33 0.33
sum(round(c(0.333, 0.333, 0.334), 2))
#> [1] 0.99
round_preserve_sum(c(0.333, 0.333, 0.334), 2)
#> [1] 0.33 0.33 0.34
sum(round_preserve_sum(c(0.333, 0.333, 0.334), 2))
#> [1] 1