ENA accession to URL

accession2url.R

accession2url <- function(x) {
  prefix <- "ftp://ftp.sra.ebi.ac.uk/vol1/fastq"
  dir1 <- paste0("/",substr(x,1,6))
  dir2 <- ifelse(nchar(x) == 9, "",
          ifelse(nchar(x) == 10, paste0("/00",substr(x,10,10)),
          ifelse(nchar(x) == 11, paste0("/0",substr(x,10,11)),
                                 paste0("/",substr(x,10,12)))))
  paste0(prefix,dir1,dir2,"/",x)
}