Hi r-devels,
I am a bit puzzled by the behaviour of cat() --- any help is appreciated...
At least AFAICS, cat() for vector-valued '...' argument behaves in
contradiction to what I understand from the note in the help to cat()
which reads
"
Despite its name and earlier documentation, 'sep' is a vector of
terminators rather than separators, being output after every
vector element (including the last). Entries are recycled as
needed.
"
----------------------------------------------------------------------------
reproducible example code:
----------------------------------------------------------------------------
>cat(rep("x",3), sep = ".")
x.x.x
## no "." appended!
Things get even worse if "\n" features in the 'sep' vector:
>cat(rep("x",3),sep = c(".","\n","."))
x.x
x
>
## last separator "." gets swallowed; an non-intended line feed is
inserted
----------------------------------------------------------------------------
code causing this behaviour
----------------------------------------------------------------------------
##### "\n"
I have looked a bit into the source code
(lines 468-630 in builtin.c in src/main)
and found out, as variable pwidth is set to 1 in line 504, i.e.;
if (strstr(CHAR(STRING_ELT(sepr, i)), "\n")) nlsep = 1; /* ASCII */
the code in lines 622-23, i.e.;
if ((pwidth != INT_MAX) || nlsep)
Rprintf("\n");
is responsible for the newline. Is this really intended?
##### separators, not terminators
Another look shows that, contrary to what is said in the help file,
an element of vector 'sep' is /not/ printed out after each element
of the vector passed as argument '...' to cat(), "including the last"
--- confer the for-loop over the elements of '...' in lines 596-617
and the print-out of the separator
cat_printsep(sepr, ntot);
in line 600. Once again: Is this intended?
A patch fixing my problem would be easy, though might crash
other much more important code; would you have any
proposals?
Best,
Peter
-------------------------------------------------------------------
Version:
platform = i386-pc-mingw32
arch = i386
os = mingw32
system = i386, mingw32
status = Under development (unstable)
major = 2
minor = 9.0
year = 2008
month = 10
day = 01
svn rev = 46589
language = R
version.string = R version 2.9.0 Under development (unstable)
(2008-10-01 r46589)
Windows XP (build 2600) Service Pack 3
Locale:
LC_COLLATE=German_Germany.1252;LC_CTYPE=German_Germany.1252;LC_MONETARY=German_Germany.1252;LC_NUMERIC=C;LC_TIME=German_Germany.1252
Search Path:
.GlobalEnv, package:stats, package:graphics, package:grDevices,
package:utils, package:datasets, package:methods, Autoloads, package:base
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