similar to: Parsing regular expressions differently - feature request

I thought that I can use metacharacters such as \w to match word characters with one backslash. But for some reason, I need to include two backslashes. > grepl(pattern='\w', x="what") Error: '\w' is an unrecognized escape in character string starting "\w" > grepl(pattern='\\w', x="what") [1] TRUE I can't find the reason for this

Hello, I have several strings where I am trying to eliminate the period and everything after the period, using a regular expression. However, I am having trouble getting this to work. > x = "wa.w" > gsub(x, "\..*", "", perl=TRUE) [1] "" Warning messages: 1: '\.' is an unrecognized escape in a character string 2: unrecognized escape removed

Hi, I guess the backslash should not be used as the separator for strsplit() in compareVersion(), because the period in [.] is no longer a metacharacter (no need to "escape" it using a backslash): https://github.com/wch/r-source/blob/trunk/src/library/utils/R/packages.R#L866-L867 > compareVersion function (a, b) { .... a <- as.integer(strsplit(a, "[\\.-]")[[1L]])

Why sometimes one has to put a double backslash in regular expressions, but often simple backslashes work too? Is only a \ required for giving a metacharacter its usual meaning? --------------------------------------- u=grep('\\{[\\-u]x',a,perl=T) # equivalent to u=grep('\{[\-u]x',a,perl=T) # but u=grep('\w',a,perl=T) # is not correct and requires

Hi folks, Can anyone enlighten me as to why I get the following when I search for ".csv" at the end of a string? > grep("\.csv$","Blah.csv",value=TRUE) [1] "Blah.csv" Warning messages: 1: '\.' is an unrecognized escape in a character string 2: unrecognized escape removed from "[\.]csv$" R reference for regular expressions says

Hi all, > diff_operator <- "\\(" > strsplit(cond, diff_operator) [[1]] [1] "andsin" "log_angle_1_4)" > diff_operator <- "\\sin(" > strsplit(cond, diff_operator) Error in strsplit(cond, diff_operator) : invalid regular expression '\sin(', reason 'Missing ')'' When I am going to split with "("

Full_Name: FAN Version: 2.4.0 OS: Windows Submission from: (NULL) (159.50.101.9) These are expected: > grep("[\-|c]", c("a-a","b")) [1] 1 > gsub("[\-|c]", "&", c("a-a","b")) [1] "a&a" "b" but these are strange: > grep("[d|\-|c]", c("a-a","b")) integer(0)

Hi there, ubuntu 18.04.2, trying to compile R-devel 3.6.0, svn 76155. I am having difficulty compiling R. I think I have pcre installed correctly: OK~/Downloads/R-devel pcretest -C PCRE version 8.41 2017-07-05 Compiled with 8-bit support UTF-8 support No Unicode properties support No just-in-time compiler support Newline sequence is LF \R matches all Unicode newlines Internal

Hi, I would really like to have a way to split long string literals across multiple lines in R. Currently, if a string literal spans multiple lines, there is no way to inhibit the introduction of newline characters: > "aaa + bbb" [1] "aaa\nbbb" If a line ends with a backslash, it is just ignored: > "aaa\ + bbb" [1] "aaa\nbbb" We could use

Hi, I am trying to use sub, regexpr on expressions like log(D) ~ log(N)+I(log(N)^2)+log(t) being a model specification. The aim is to produce: "ln D ~ ln N + ln^2 N + ln t" The variable names N, t may change, the number of terms too. I succeded only partially, help on regular expressions is hard to understand for me, examples on my case are rare. The help page on R-help

Railsters: ActiveRecord''s validation system puts other database systems to shame. However, the newbies might not know how to write a regexp that excludes a match, instead of tests for it. Understand - I''m just asking this question to help them. I have been using Regexps since ''grep'' on Xenix! But the newbies here might not know how to do this:

Ok, I''m hoping this won''t be a forehead slapper, but take a look at this code: physician.name.sub(/''/, "\\''") I''m trying to substitute a single quote with a backslash and a single quote. This seems pretty simple right? Well, someone kick me and tell me why it''s not :) Here''s what I''m getting if the

Here is my interaction with R: > sub(x='>|t|',pattern = '|t',replacement='zz') [1] "zz>|t|" So I say to myself "Clearly the | signs need to be escaped, so let's try this" > sub(x='>|t|',pattern = '\|t',replacement='zz') [1] "zz>|t|" Warning messages: 1: '\|' is an unrecognized escape in a

On Wed, 14 Jun 2017 06:12:09 -0500, Duncan Murdoch <murdoch.duncan at gmail.com> wrote: > On 14/06/2017 5:58 AM, Andreas Kersting wrote: > > Hi, > > > > I would really like to have a way to split long string literals across > > multiple lines in R. > > I don't understand why you require the string to be a literal. Why not > construct the long

thanks for this guys. I only compiled pcre myself as a last resort, because of the ./configure failure. But AFAICS apt-get reports correct installation: OK~/Downloads/R-devel sudo apt-get install r-base-dev Reading package lists... Done Building dependency tree Reading state information... Done r-base-dev is already the newest version (3.5.2-1cosmic). 0 upgraded, 0 newly installed, 0 to

thanks for this guys. I only compiled pcre myself as a last resort, because of the ./configure failure. But AFAICS apt-get reports correct installation: OK~/Downloads/R-devel sudo apt-get install r-base-dev Reading package lists... Done Building dependency tree Reading state information... Done r-base-dev is already the newest version (3.5.2-1cosmic). 0 upgraded, 0 newly installed, 0 to

> On Tuesday 09 June 2009 04:35, Török Edwin wrote: > > On 2009-06-09 12:27, Howard Su wrote: > > > This change break the MSVC build since no regex by default in Windows > > > MSVC platform. > > > > Perhaps we should add a regex implementation to lib/System? > > That's potentially a lot of work. I started looking at it and it would > involve

OK thanks Tomas, but I get OK~ sudo apt-get build-dep r-base Reading package lists... Done E: Unable to find a source package for r-base OK~ hankin.robin at gmail.com On Fri, Mar 1, 2019 at 8:47 PM Tomas Kalibera <tomas.kalibera at gmail.com> wrote: > > On 3/1/19 7:10 AM, robin hankin wrote: > > thanks for this guys. > > > > I only compiled pcre myself as a last

OK thanks Tomas, but I get OK~ sudo apt-get build-dep r-base Reading package lists... Done E: Unable to find a source package for r-base OK~ hankin.robin at gmail.com On Fri, Mar 1, 2019 at 8:47 PM Tomas Kalibera <tomas.kalibera at gmail.com> wrote: > > On 3/1/19 7:10 AM, robin hankin wrote: > > thanks for this guys. > > > > I only compiled pcre myself as a last

Hello, when I use list.files with recursive = TRUE and all.files = TRUE, R returns a list of strings/paths. >From all those strings I want to keep only the ones starting with a . I tried using grep to achieve that. However, the problem is that because of the recursive list.files parameter, for some files beginning with a . there is a path attached. I think it is not as simple as it looks