Sha256: 455bba84346d82d0659faf251e4ffe43b54289f0f8962fc895cd31abb4efd46a
Contents?: true
Size: 1001 Bytes
Versions: 41
Compression:
Stored size: 1001 Bytes
Contents
# Convert a number to a valid number, if it isn't already.
luhn <- function(input) {
if (is_valid(input)) {
return(input)
}
diff <- (10 - checksum(10*input)) %% 10
return(10 * input + diff)
}
# Get the check digit
check_digit <- function(input) {
as.numeric(substring(input,nchar(input)))
}
# Compute the checksum
checksum <- function(input) {
sum(addends(input))
}
# Determine whether the number is valid.
is_valid <- function(input) {
checksum(input) %% 10 == 0
}
# addends returns the vector of numbers that follow the luhn algorithm
addends <- function(input) {
check <- check_digit(input)
v <- as.numeric(strsplit(as.character(input),"")[[1]])
# counting from right double value of every second digit
start_seq <- ifelse(length(v) %% 2 == 1, 0, 1)
v2 <- replace(v,seq(start_seq,length(v),2),v[seq(start_seq,length(v),2)]*2)
v2 <- ifelse(v2 > 9, v2 - 9, v2)
replace_vals <- v2[seq(start_seq,length(v),2)]
replace(v,seq(start_seq,length(v),2),replace_vals)
}
Version data entries
41 entries across 41 versions & 1 rubygems