readLines unknown n

Question

While in a gui (be it Windows gui or RStudio etc) I can use readLines from a script with a known number of lines as seen below by specifying n=?. What if I am unsure of the number of lines being read (i.e., I have a lot of lines and don't know n). How can I use readLines in a gui (read from a script within not an outside file) without specifying n? If you don't supply n it appears readLines keeps the connection open and keeps on reading lines. Hitting esc stops the function but no lines are read.

x <- readLines(n=4)
** preparing package for lazy loading
** help
*** installing help indices
** building package indices

x

Here is a video demoing the specific problem I am asking.

This is particularly useful when a poster gives you data in an odd format like the set below and you want to read it in without counting all the rows:

** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices

EDIT Until this gets reopened and Dason can answer himself...

Dason suggests using ctrl + z and this works (at least on a Windows machine)

You don't need to specify the number of lines. It keeps reading until the connection stops supplying. — IRTFM, Apr 16 '13 at 02:17
It reads to the end of the file. (I must be missing a crucial bit of perspective. You are able to open a connection to an edit buffer?) — IRTFM, Apr 16 '13 at 02:19
Yes that works nicely with an external .R/.txt file but what about reading select lines from a script within something like RStudio. it just keeps reading lines. — Tyler Rinker, Apr 16 '13 at 02:22
Just did, no dice. I am uploading a video to youtube to share to demo the problem more clearly as I think I'm not expressing the issue properly. — Tyler Rinker, Apr 16 '13 at 02:30
Voting to close without a statement of why or a downvote is unhelpful. To the downvoter and closers did you look at the video? — Tyler Rinker, Apr 16 '13 at 02:50
In the windows GUI shown in the video, I had luck with Ctrl-z — Martin Morgan, Apr 16 '13 at 03:06
@TylerRinker Maybe they just think you're a horrible creature made of concentrated hatred and deserve to have imaginary internet points taken away. Just sayin' ;) — Dason, Apr 16 '13 at 03:12
possible duplicate of [Code to import data from a Stack overflow query into R](http://stackoverflow.com/questions/10849270/code-to-import-data-from-a-stack-overflow-query-into-r) — GSee, Apr 16 '13 at 11:48
@GSee that is a typically formatted dataframe the question specifically says `an odd format` — Tyler Rinker, Apr 16 '13 at 23:29
Since I can't add an actual answer anymore - ctrl+z does what Tyler wants to do (at least on Windows) — Dason, May 03 '13 at 14:08
On Mac or Linux, ctrl + z immediately terminates the R session. :-/ — GSee, May 10 '13 at 00:45

score 1 · Answer 1 · edited Apr 16 '13 at 03:17

Two easy solutions.

Put the text into another file, and read that.
Don't use readLines. Quote the text:

x <- strsplit("** preparing package for lazy loading
** help
*** installing help indices
** building package indices
", "\n")


x
[[1]]
[1] "** preparing package for lazy loading" "** help"                               "*** installing help indices"          
[4] "** building package indices"

score 1 · Answer 2 · answered Apr 16 '13 at 03:12

You can wrap quotes around the text and create a textConnection to read

text <- "** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** preparing package for lazy loading
** help
*** installing help indices
** building package indices"

readLines(textConnection(text))
# [1] "** preparing package for lazy loading" "** help"                              
# [3] "*** installing help indices"           "** building package indices"          
# [5] "** preparing package for lazy loading" "** help"                              
# [7] "*** installing help indices"           "** building package indices"          
# [9] "** preparing package for lazy loading" "** help"                              
#[11] "*** installing help indices"           "** building package indices"          
#[13] "** preparing package for lazy loading" "** help"                              
#[15] "*** installing help indices"           "** building package indices"          
#[17] "** preparing package for lazy loading" "** help"                              
#[19] "*** installing help indices"           "** building package indices"

I think this is closest to the spirit of what I was trying to accomplish with the least amount of work. — Tyler Rinker, Apr 16 '13 at 03:14

score 1 · Answer 3 · answered Apr 16 '13 at 06:47

1

In a Windows environment after selecting and copying to the clipboard:

 (clip.input <- readLines( file("clipboard") ) )

In a Mac/UNIX:

 (clip.input <- readLines( pipe("pbpaste") ) )

answered Apr 16 '13 at 06:47

IRTFM

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readLines unknown n

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