# Generating unique random IDs

**Matt's Stats n stuff » R**, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)

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Recently I was asked to help create random IDs for someone. At first I thought, ‘Ah yup, 1:x (1,2,3, …,x), job done’. Then I thought that there had to be a R function/package to create better looking IDs, to which I didn’t find one, if there is, please let me know.

In the mean time I wrote this, which puts a random letter at the start, followed by random (shuffled) numbers. Using ‘sprintf’ allows the keeping in of leading 0′s, this way all your ID’s are the same character width, multiplying by 100 is purely to avoid having small (<3) ID’s created, this can be changed to 1, if you choose. Not 100% on the reason for leading with a letter, but it seems common in ID’s, perhaps to avoid something like ‘id_col/3′ actually running if you used only numbers…

idmaker <- function(x) { max.val = x*100 count <- nchar(as.character(max.val)) # find out how many 'numbers' each ID will have after the letter size <- paste("%0",count,"d",sep="") # set the variable to be fed into 'sprintf' to ensure we have leading 0's lets <- toupper(sample(letters,x, replace=T)) # randomising the letters nums <- sprintf(size,sample(1:max.val)[1:x]) # randominsing the numbers, and ensuing they all have the same number of characters ids <- paste(lets,nums,sep="") # joining them together return(ids) }

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