Hi, I have a simple question. Suppose I have a string "x$Expensive". I want to find the position of the $ in this string; i.e., I want a function that returns 2. I tried grep, regexpr, etc with no luck, unless I'm just using them incorrectly. Any suggestions? Thanks, Walt ________________________ Walter R. Paczkowski, Ph.D. Data Analytics Corp. 44 Hamilton Lane Plainsboro, NJ 08536 ________________________ (V) 609-936-8999 (F) 609-936-3733 walt at dataanalyticscorp.com www.dataanalyticscorp.com
pattern matching
4 messages · Data Analytics Corp., arun, Marc Schwartz +1 more
HI,
str1<-"x$Expensive"
regexpr("\\$",str1)[1]
#[1] 2
?str2<-"x$Exp$Expression"
unlist(gregexpr("\\$",str2))
#[1] 2 6
A.K.
----- Original Message -----
From: Data Analytics Corp. <walt at dataanalyticscorp.com>
To: "r-help at R-project.org" <r-help at r-project.org>
Cc:
Sent: Monday, January 7, 2013 4:22 PM
Subject: [R] pattern matching
Hi,
I have a simple question.? Suppose I have a string "x$Expensive". I want to find the position of the $ in this string; i.e., I want a function that returns 2.? I tried grep, regexpr, etc with no luck, unless I'm just using them incorrectly.? Any suggestions?
Thanks,
Walt
________________________
Walter R. Paczkowski, Ph.D.
Data Analytics Corp.
44 Hamilton Lane
Plainsboro, NJ 08536
________________________
(V) 609-936-8999
(F) 609-936-3733
walt at dataanalyticscorp.com
www.dataanalyticscorp.com
______________________________________________
R-help at r-project.org mailing list
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On Jan 7, 2013, at 3:22 PM, Data Analytics Corp. <walt at dataanalyticscorp.com> wrote:
Hi, I have a simple question. Suppose I have a string "x$Expensive". I want to find the position of the $ in this string; i.e., I want a function that returns 2. I tried grep, regexpr, etc with no luck, unless I'm just using them incorrectly. Any suggestions? Thanks, Walt
The problem with this specific example is that '$' is a metacharacter in regular expressions, so you have to escape it. For example:
regexpr("\\$", "x$Expensive")
[1] 2 attr(,"match.length") [1] 1 attr(,"useBytes") [1] TRUE See ?regex for more information and if appropriate, consider gregexpr():
gregexpr("\\$", "x$Expensive$MoreText")
[[1]] [1] 2 12 attr(,"match.length") [1] 1 1 attr(,"useBytes") [1] TRUE Regards, Marc Schwartz
"$" has a special meaning (end-of-string) in regular expressions, so you can either escape it with "\\" or not use regular expressions in regexpr():
regexpr("\\$", "x$Expensive")
[1] 2 attr(,"match.length") [1] 1 attr(,"useBytes") [1] TRUE
regexpr("$", "x$Expensive", fixed=TRUE)
[1] 2 attr(,"match.length") [1] 1 attr(,"useBytes") [1] TRUE Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com
-----Original Message----- From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Data Analytics Corp. Sent: Monday, January 07, 2013 1:22 PM To: r-help at R-project.org Subject: [R] pattern matching Hi, I have a simple question. Suppose I have a string "x$Expensive". I want to find the position of the $ in this string; i.e., I want a function that returns 2. I tried grep, regexpr, etc with no luck, unless I'm just using them incorrectly. Any suggestions? Thanks, Walt
________________________ Walter R. Paczkowski, Ph.D. Data Analytics Corp. 44 Hamilton Lane Plainsboro, NJ 08536 ________________________ (V) 609-936-8999 (F) 609-936-3733 walt at dataanalyticscorp.com www.dataanalyticscorp.com ______________________________________________ R-help at 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.