On 2025-06-25 10:10 a.m., Jeff Newmiller via R-help wrote:
As a longtime programmer, I would say that your file is at fault... there is no
programming standard that says any software needs to handle this kind of data
in any defined way.
The documentation for readLines() says this:
"Whatever mode the connection is opened in, any of LF, CRLF or CR will
be accepted as the EOL marker for a line."
Perhaps that needs to be clarified to say that all lines in the file
need to use the same EOL marker for consistent results.
Duncan Murdoch
More specifically, the only standards-based requirements I am aware of
require the programmer to specify whether the file is a text file (per
the convention drive by the OS) or a binary file. The fact that your
file does not conform with a consistent line end mark convention means
that any "automatic" identification of line end conventions is
completely optional.
Looking at this from the perspective of a user, I think you have two options:
fix the process that is feeding you invalid data, or use binary mode to
implement the parsing behavior you wish to obtain for this file format.
In addition, I suppose you could develop a generic line end handling algorithm
that you think would resolve this and submit a suggestion/patch to R and hope
someone agrees that such a change won't cause more havoc than it avoids for
other users. But that would be unlikely to happen in a timely fashion for your
current needs.
On June 24, 2025 11:59:58 PM PDT, "Heuvel, E.G. van den (Guido) via R-help"
<r-help@r-project.org> wrote:
Hi all,
I encountered some weird behaviour with readLines() recently, and I am
wondering if this might be a bug, or, if it is not, how to resolve it. The
issue is as follows:
If I have a text file where a line ends with just a carriage return (\r, CR)
while the next line is empty and ends in a carriage return / linefeed (\r\n, CR
LF), then the empty line is skipped when reading the file with readLines. The
following code contains a test case:
---
print(R.version)
# platform x86_64-w64-mingw32
# arch x86_64
# os mingw32
# crt ucrt
# system x86_64, mingw32
# status
# major 4
# minor 4.0
# year 2024
# month 04
# day 24
# svn rev 86474
# language R
# version.string R version 4.4.0 (2024-04-24 ucrt)
# nickname Puppy Cup
txt_original <- paste0("Line 1\r", "\r\n", "Line 3\r\n")
# Write txt_original as binary to avoid unwanted conversion of end of line
markers
writeBin(charToRaw(txt_original), "test.txt")
txt_actual <- readLines("test.txt")
print(txt_actual)
# [1] "Line 1" "Line 3"
---
I included the output of this script on my machine in the comments. I would expect txt_actual to be equal to
c("Line 1", "", "Line 3"), but the empty line is skipped.
Is this a bug? And if not, how should I read test.txt in such a way that the
empty 2nd line is left intact?
Best regards,
Guido van den Heuvel
Statistics Netherlands
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