Re: [R] Using grep() to subset lines of text
ppaarrkk wrote: I have two vectors, a and b. b is a text file. I want to find in b those elements of a which occur at the beginning of the line in b. I have the following code, but it only returns a value for the first value in a, but I want both. Any ideas please. a = c(2,3) b = NULL b[1] = aaa 2 aaa b[2] = 2 aaa b[3] = 3 aaa b[4] = aaa 3 aaa grep(paste(^,a, sep=), b ) grep(paste(^, a, collapse = |, sep = ), b) Uwe Ligges __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] Using grep() to subset lines of text
I have two vectors, a and b. b is a text file. I want to find in b those elements of a which occur at the beginning of the line in b. I have the following code, but it only returns a value for the first value in a, but I want both. Any ideas please. a = c(2,3) b = NULL b[1] = aaa 2 aaa b[2] = 2 aaa b[3] = 3 aaa b[4] = aaa 3 aaa grep(paste(^,a, sep=), b ) -- View this message in context: http://www.nabble.com/Using-grep%28%29-to-subset-lines-of-text-tp20746365p20746365.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Using grep() to subset lines of text
Try this: a - 2:3 b - c(aaa 2 aaa, 2 aaa, 3 aaa, aaa 3 aaa) re - paste(^(, paste(a, collapse = |), ), sep = ) re [1] ^(2|3) grep(re, b, value = TRUE) [1] 2 aaa 3 aaa On Sat, Nov 29, 2008 at 7:00 AM, ppaarrkk [EMAIL PROTECTED] wrote: I have two vectors, a and b. b is a text file. I want to find in b those elements of a which occur at the beginning of the line in b. I have the following code, but it only returns a value for the first value in a, but I want both. Any ideas please. a = c(2,3) b = NULL b[1] = aaa 2 aaa b[2] = 2 aaa b[3] = 3 aaa b[4] = aaa 3 aaa grep(paste(^,a, sep=), b ) -- View this message in context: http://www.nabble.com/Using-grep%28%29-to-subset-lines-of-text-tp20746365p20746365.html Sent from the R help mailing list archive at Nabble.com. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Using grep() to subset lines of text
Hmm, this brings up an interesting question. What if the string I'm looking for contains escape characters? For example, grep( paste( ^, (ab) ), c(ab,(ab)) ) = c(1), not c(2). I couldn't find an equivalent to Emacs's regexp-quote, which would let me write regexp.quote((ab)) = \\(ab\\). The syntax of regular expressions is complicated enough that this is not trivial. Is there perhaps a CRAN package with regular expression utilities? -s On Sat, Nov 29, 2008 at 7:12 AM, Gabor Grothendieck [EMAIL PROTECTED] wrote: a - 2:3 b - c(aaa 2 aaa, 2 aaa, 3 aaa, aaa 3 aaa) re - paste(^(, paste(a, collapse = |), ), sep = ) grep(re, b, value = TRUE) [1] 2 aaa 3 aaa [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Using grep() to subset lines of text
grep has a fixed = TRUE argument if you want to ignore all regexp's. On Sat, Nov 29, 2008 at 3:55 PM, Stavros Macrakis [EMAIL PROTECTED] wrote: Hmm, this brings up an interesting question. What if the string I'm looking for contains escape characters? For example, grep( paste( ^, (ab) ), c(ab,(ab)) ) = c(1), not c(2). I couldn't find an equivalent to Emacs's regexp-quote, which would let me write regexp.quote((ab)) = \\(ab\\). The syntax of regular expressions is complicated enough that this is not trivial. Is there perhaps a CRAN package with regular expression utilities? -s On Sat, Nov 29, 2008 at 7:12 AM, Gabor Grothendieck [EMAIL PROTECTED] wrote: a - 2:3 b - c(aaa 2 aaa, 2 aaa, 3 aaa, aaa 3 aaa) re - paste(^(, paste(a, collapse = |), ), sep = ) grep(re, b, value = TRUE) [1] 2 aaa 3 aaa __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Using grep() to subset lines of text
But I don't want to ignore all regexp's -- I want to build a regexp which contains string components which are parameters. -s On Sat, Nov 29, 2008 at 6:51 PM, Gabor Grothendieck [EMAIL PROTECTED] wrote: grep has a fixed = TRUE argument if you want to ignore all regexp's. On Sat, Nov 29, 2008 at 3:55 PM, Stavros Macrakis [EMAIL PROTECTED] wrote: Hmm, this brings up an interesting question. What if the string I'm looking for contains escape characters? For example, grep( paste( ^, (ab) ), c(ab,(ab)) ) = c(1), not c(2). I couldn't find an equivalent to Emacs's regexp-quote, which would let me write regexp.quote((ab)) = \\(ab\\). The syntax of regular expressions is complicated enough that this is not trivial. Is there perhaps a CRAN package with regular expression utilities? -s On Sat, Nov 29, 2008 at 7:12 AM, Gabor Grothendieck [EMAIL PROTECTED] wrote: a - 2:3 b - c(aaa 2 aaa, 2 aaa, 3 aaa, aaa 3 aaa) re - paste(^(, paste(a, collapse = |), ), sep = ) grep(re, b, value = TRUE) [1] 2 aaa 3 aaa [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Using grep() to subset lines of text
Try this. For each character x in s, if x is punctuation it is replaced
with \\x otherwise with [x] :
library(gsubfn)
gsubfn('.', ~ if (any(grep([[:punct:]], x))) paste0('\\', x) else
paste0('[', x, ']'), s)
See http://gsubfn.googlecode.com
On Sat, Nov 29, 2008 at 10:09 PM, Stavros Macrakis
[EMAIL PROTECTED] wrote:
But I don't want to ignore all regexp's -- I want to build a regexp which
contains string components which are parameters.
-s
On Sat, Nov 29, 2008 at 6:51 PM, Gabor Grothendieck
[EMAIL PROTECTED] wrote:
grep has a fixed = TRUE argument if you want to ignore all regexp's.
On Sat, Nov 29, 2008 at 3:55 PM, Stavros Macrakis [EMAIL PROTECTED]
wrote:
Hmm, this brings up an interesting question. What if the string I'm
looking
for contains escape characters? For example, grep( paste( ^, (ab)
),
c(ab,(ab)) ) = c(1), not c(2).
I couldn't find an equivalent to Emacs's regexp-quote, which would let
me
write regexp.quote((ab)) = \\(ab\\). The syntax of regular
expressions
is complicated enough that this is not trivial. Is there perhaps a CRAN
package with regular expression utilities?
-s
On Sat, Nov 29, 2008 at 7:12 AM, Gabor Grothendieck
[EMAIL PROTECTED] wrote:
a - 2:3
b - c(aaa 2 aaa, 2 aaa, 3 aaa, aaa 3 aaa)
re - paste(^(, paste(a, collapse = |), ), sep = )
grep(re, b, value = TRUE)
[1] 2 aaa 3 aaa
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