What do you mean by "doesn't work" and "the \\" are removed?
> a <- "..\\/path\\/file"
> a
[1] "..\\/path\\/file"
> cat(a)
..\/path\/file
--
David Winsemius
On Nov 26, 2008, at 7:46 PM, ikarus wrote:
Thanks Sean!!
I followed you suggestion to use gsub() and it worked perfectly!
I still can't create a string with inside "\/" (e.g., a <-
"..\\/path\\/file"
doesn't work, R complains and the \\ are removed), but I don't care,
gsub() does the same job as sed and without using any system call.
seanpor wrote:
Good morning,
You do not need to quote a forward slash / in R, but you do need to
quote
a backslash when you're inputting it... so to get a string which
actually
contains "blah\/blah"... you need to use "blah\\/blah"
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-does-backslash-behave-strangely-inside-strings_003f
Unless this is a very very big file you shouldn't need to go out to
sed,
as gsub() should work adequately... and probably quicker and
cleaner. So
something along the lines of.. (UNTESTED!!! since I don't have a
reproduceable example)
tmp1 <- readLines(configurationFile)
tmp1 <- gsub("^instance .*", paste("instance = ", data
$instancePath, "/",
data$newInstance, sep = ""), tmp1)
I'm working on 50mb text files, and doing all sorts of
manipulations and I
do it all inside R under windows XP... reading a 50mb text file
across
the 100mb network and doing a gsub() on most lines takes an elapsed
16
seconds on this office desktop.
hth...
Regards,
Sean
ikarus wrote:
Hi guys,
I've been struggling to find a solution to the following issue:
I need to change strings in .ini files that are given in input to a
program whose output is processed by R. The strings to be changed
looks
like:
"instance = /home/TSPFiles/TSPLIB/berlin52.tsp"
I normally use Sed for this kind of things. So, inside R I'd like to
write something like:
command <- paste("sed -i 's/^instance .*/instance = ",
data$instancePath,
data$newInstance, "/' ", configurationFile, sep
= "")
system(command)
This will overwrite the line starting with "instance " using
"instance =
the_new_instance"
In the example I gave, data$instancePath = /home/TSPFiles/TSPLIB/
and
data$newInstance = berlin52.tsp
The problem is that I need to pass the above path string to sed in
the
form:
"\/home\/TSPFiles\/TSPLIB\/"
However, I couldn't find a way to "create" such a string in R. I
tried in
several different ways,
but it always complains saying that '\/' is an unrecognized escape!
Any suggestion?
Thanks!
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