[R] Looking for simple line-splitting code

[Rui Barradas]

Hello,

Inline.

Às 20:27 de 05/02/2025, peter dalgaard escreveu:
> A 3rd option could be
> 
> scan(text=x, what="", blank.lines.skip=FALSE)
> 
> (all because readLines() doesn't obey the text=x convention, perhaps it should? I'm unsure whether the textConnection is left open in Rui's method.)

No, it is not left open. Use ?showConnections to check it.


x <- c("abc\ndef", "", "ghi")

x |> textConnection() |> readLines()
showConnections()

# this creates and opens a connection
tc <- textConnection(x)
showConnections()
readLines(tc)
showConnections()
close(tc)
showConnections()


Hope this helps,

Rui Barradas

> 
> -pd
> 
>> On 5 Feb 2025, at 15:35 , Duncan Murdoch <murdoch.duncan using gmail.com> wrote:
>>
>> Thanks to Rui, Peter and Tanvir!  Peter's seems to be the fastest of the 3 suggestions so far on the little test case, but on the real data (where x contains several thousand lines), Rui's seems best.
>>
>> Duncan
>>
>> On 2025-02-05 9:13 a.m., peter dalgaard wrote:
>>> This also seems to work:
>>>> strsplit(paste(x,collapse="\n"),"\n")[[1]]
>>> [1] "abc" "def" ""    "ghi"
>>>> On 5 Feb 2025, at 14:44 , Duncan Murdoch <murdoch.duncan using gmail.com> wrote:
>>>>
>>>> If I have this object:
>>>>
>>>>   x <- c("abc\ndef", "", "ghi")
>>>>
>>>> and I write it to a file using `writeLines(x, "test.txt")`, my text editor sees a 5 line file:
>>>>
>>>>   1: abc
>>>>   2: def
>>>>   3:
>>>>   4: ghi
>>>>   5:
>>>>
>>>> which is what I'd expect:  the last line in the editor is empty.  If I use `readLines("test.txt")` on that file, I get the vector
>>>>
>>>>   c("abc", "def", "", "ghi")
>>>>
>>>> and all of that is fine.
>>>>
>>>> What I'm looking for is simple code that modifies x to the `readLines()` output, without actually writing and reading it.
>>>>
>>>> My first attempt doesn't work:
>>>>
>>>>   unlist(strsplit(x, "\n"))
>>>>
>>>> because it leaves out the blank line 3.  I can fix that with this ugly code:
>>>>
>>>>   lines <- strsplit(x, "\n")
>>>>   lines[sapply(lines, length) == 0] <- list("")
>>>>   lines <- unlist(lines)
>>>>
>>>> Surely there's a simpler way to do this?  I'd like to use just base functions, no other packages.
>>>>
>>>> Duncan Murdoch
>>>>
>>>> ______________________________________________
>>>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide https://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>
> 


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