Generating Random Strings

Question

I want to generate random strings in the following way: ABCDE1234E, i.e each string contains 5 Characters, 4 Numerics, then 1 Char.

I figured out a way to create this using the following code.

library(random) string_5 <- as.vector(randomStrings(n=5000, len=5, digits=FALSE, upperalpha=TRUE,                         loweralpha=FALSE, unique=TRUE, check=TRUE)) number_4 <- as.vector(randomNumbers(n=5000, min=1111, max=9999, col=5, base=10, check=TRUE)) string_1 <- as.vector(randomStrings(n=5000, len=1, digits=FALSE, upperalpha=TRUE,                          loweralpha=FALSE, unique=FALSE, check=TRUE)) PAN.Number <- paste(string_5,number_4,string_1,sep = "") 

But these functions are taking a long time and the random library needs a network connection.

> system.time(string_5 <- as.vector(randomStrings(n=5000, len=5, digits=FALSE, upperalpha=TRUE, +                                                 loweralpha=FALSE, unique=TRUE, check=TRUE)))    user  system elapsed     0.07    0.00    3.18  

Is there any method that I could try to reduce the execution time? I also tried using sample() but I couldn't figure it out.

Answer 1

Using "stringi" as suggested by @akrun will be faster, but the following is also very fast and does not require any additional packages:

myFun <- function(n = 5000) {   a <- do.call(paste0, replicate(5, sample(LETTERS, n, TRUE), FALSE))   paste0(a, sprintf("%04d", sample(9999, n, TRUE)), sample(LETTERS, n, TRUE)) } 

Example output:

myFun(10) ##  [1] "BZHOF3737P" "EPOWI0674X" "YYWEB2825M" "HQIXJ5187K" "IYIMB2578R" ##  [6] "YSGBG6609I" "OBLBL6409Q" "PUMAL5632D" "ABRAT4481L" "FNVEN7870Q" 

Answer 2

We can use stri_rand_strings from stringi

library(stringi) sprintf("%s%s%s", stri_rand_strings(5, 5, '[A-Z]'),       stri_rand_strings(5, 4, '[0-9]'), stri_rand_strings(5, 1, '[A-Z]')) 

---

Or more compactly

do.call(paste0, Map(stri_rand_strings, n=5, length=c(5, 4, 1),             pattern = c('[A-Z]', '[0-9]', '[A-Z]'))) 

Benchmarks

system.time({     do.call(paste0, Map(stri_rand_strings, n=5000, length=c(5, 4, 1),             pattern = c('[A-Z]', '[0-9]', '[A-Z]')))     }) #  user  system elapsed  #   0      0      0 

Was able to reproduce the timings even for one part of the expected output using OP's method

system.time(string_5 <- as.vector(randomStrings(n=5000, len=5, digits=FALSE, upperalpha=TRUE,                                               loweralpha=FALSE, unique=TRUE, check=TRUE))) #  user  system elapsed  #   0.86    0.24    5.52