How to convert list.files() output to an int?

Question

The output when checking an empty directory with R's list.files() is a character string...

> list.files('/home/someDir')
character(0)

But I would like to test its length and use it in a control structure like

> current <- '/home/someDir'
> dirPick <- function(){
    tryCatch(
      if (length(list.files(current) > 0)) {
        dirData <- current
      } else {
        dirData <- old
      }
    )
  }

But the object returned by list.files() doesn't act like I'd expect:

> list.files('/home/someDir') == 0
logical(0)


> as.numeric(list.files('/home/someDir')) == 0
logical(0)

Not sure I understand the difference between a logical and boolean, but why doesn't this just act like an integer zero?

score 2 · Answer 1 · answered Apr 14 '17 at 17:39

2

Try:

length(list.files('/home/someDir')) == 0

The value character(0) indicates some like an empty variable. Thats why you can't sum or convert it into 0 without length() attribute

answered Apr 14 '17 at 17:39

gonzalez.ivan90

1,322
1
12
22

Or `!length(...)` though that may be less readable. – Frank Apr 14 '17 at 17:57

How to convert list.files() output to an int?

1 Answers1