passing a number with leading zeroes to function

Question

I am trying to write a function that has an argument like below:

myfunction<-function(id){
print(paste(id, ".", "csv", sep=""))
}

when the id value is like this 009, it prints it as 9.csv not 009.csv.

I tried this:

id<-as.character(id)

this is not working. Any suggestions?

Answer 1

Use e.g. sprintf():

myfunction <- function(id) {
    sprintf("%03d.csv", id)
}

which gives

R> cat(myfunction(9), "\n")
009.csv 
R> cat(myfunction(199), "\n")
199.csv 
R> 

Answer 2

Although you already accepted @Dirk's answer...

The problem is you are passing your input as a numeric. For R, 009 evaluates to 9:

> 009
[1] 9

so when you run myfunction(009), it really runs myfunction(9). It should be no surprise you get "9.csv" as your output.

Instead, you should pass your input as a character: "009":

> myfunction("009")
[1] "009.csv"