Digit sum function in R

Question

I was looking for the quite basic numeric function digit sum in R.

• I did not find a preinstalled function.
• Even in Stackoverflow's extensive R library I did not find a record.

Therefore tried myself ending with following function:

# Function to calculate a digit sum
digitsum = function (x) {sum(as.numeric(unlist(strsplit(as.character(x), split="")))) }

I works, but I still struggle with following two questions:

1. Is there really in plain R no function for digit sum?
2. Is there a smarter way to code this function?

Answer 1

This should be better:

digitsum <- function(x) sum(floor(x / 10^(0:(nchar(x) - 1))) %% 10)