rfilepathillegal-characters

How to precisely check for illegal characters of file paths?

I am developing a Shiny app, which generates folders and subfolders for each user and each of their experiments.

I wish to ensure that neither the user nor experiment names contain any illegal characters.

I define a character vector with every illegal character that I know of, however, there is a chance of human errors. Is there a more precise way of doing this?

dir <- "~/home/my_app_data"
usr <- "john"
exp <- "explosion`s"
path <- paste(dir, usr, exp, sep = "/")
illegal <- c(" ", ",", "`")

if (any(illegal %in% (strsplit(x = path, split = "") %>% unlist))) {
  stop( "Illegal characters used")
} else {
  dir.create(path, recursive = T)
}
Solution

  • Using grepl. pattern="\\W" finds non-word characters excluding underscore "_".

    FUN <- function(x) {
  if (grepl("\\W", x)) stop(sprintf("Illegal characters used in '%s'", x)) else x
}

FUN(usr)
# [1] "john"

FUN(exp)
# Error in FUN(exp) : Illegal characters used in 'explosion`s'

lapply(c(usr, exp), FUN)
# Error in FUN(X[[i]], ...) : Illegal characters used in 'explosion`s' 

FUN("john123")
# [1] "john123"

FUN("john_123")
# [1] "john_123"

    (Of course you want to define your custom else condition.)