[R] Removing a dollar sign from a character vector

[William Dunlap]

In certain programs (not current R), a pattern with stuff after a naked
dollar
sign would not match anything because dollar meant end-of-string.

In any case I prefer simple rules like 'backslash a dollar sign' instead of
'backslash a dollar sign at the end of the pattern but not elsewhere'.


Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Thu, Feb 11, 2016 at 9:01 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
wrote:

> The "end of string" special meaning only applies when the dollar sign is
> at the right end of the string (as it was in the OP attempt). That is, it
> is NOT generally necessary to wrap it in brackets to remove the special
> meaning unless it would otherwise be at the end of the pattern string.
> --
> Sent from my phone. Please excuse my brevity.
>
> On February 10, 2016 10:10:40 PM PST, William Dunlap via R-help <
> r-help at r-project.org> wrote:
>
>>  y
>>>
>>    [1] "$1,000.00 " "$1,000.00 " "$1,000.00 " "$2,600.00 " "$2,600.00 "
>>
>>>  gsub("$", "", y)
>>>
>>    [1] "$1,000.00 " "$1,000.00 " "$1,000.00 " "$2,600.00 " "$2,600.00 “ #
>> no change. Why?
>>
>> "$" as a regular expression means "end of string", which has zero length -
>> replacing "end
>> of string" with nothing does not affect the string.  Try gsub("$",
>> "DOLLAR", "$100")
>> to see it do something.
>>
>> Use either fixed=TRUE so the 'pattern'  argument is not regarded as a
>> regular expression or pattern="\\$" or pattern="[$]" to remove dollar's special
>> meaning in the pattern language.
>>
>> Read up on regular expressions (probably there is a See Also
>> entry in
>> help(gsub)).
>>
>>
>> Bill Dunlap
>> TIBCO Software
>> wdunlap tibco.com
>>
>> On Wed, Feb 10, 2016 at 9:39 PM, James Plante <jimplante at me.com> wrote:
>>
>>  What I’ve got:
>>>  # sessionInfo()
>>>  R version 3.2.3 (2015-12-10)
>>>  Platform: x86_64-apple-darwin13.4.0 (64-bit)
>>>  Running under: OS X 10.11.3 (El Capitan)
>>>
>>>  locale:
>>>  [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
>>>
>>>  attached base packages:
>>>  [1] stats     graphics  grDevices utils     datasets  methods   base
>>>
>>>  other attached packages:
>>>  [1] XML_3.98-1.3 dplyr_0.4.3
>>>
>>>  loaded via a namespace (and not attached):
>>>  [1] magrittr_1.5      R6_2.1.2          assertthat_0.1    rsconnect_0.4.1.4
>>>  [5] parallel_3.2.3    DBI_0.3.1         tools_3.2.3
>>> Rcpp_0.12.3
>>>
>>>  str(y) #toy vector, subset of larger vector in a dataframe of ~4,600
>>>>
>>>  rows.
>>>   chr [1:5] "$1,000.00 " "$1,000.00 " "$1,000.00 " "$2,600.00 " "$2,600.00 “
>>>
>>>  y is a subset of a column in a dataframe that’s too big to post. I tried
>>>  the commands listed here on the dataframe and it didn’t work. So I’m using
>>>  a small subset to find out where my error is. It’s being a PITA, and I’m
>>>  trying to solve it. What I want is a vector of numbers: 1000, 1000, 1000,
>>>  2600, 2,600.
>>>
>>>  What I’ve tried:
>>>
>>>>  y
>>>>
>>>  [1] "$1,000.00 " "$1,000.00 " "$1,000.00 " "$2,600.00 " "$2,600.00 "
>>>
>>>>  gsub("$", "", y)
>>>>
>>>  [1] "$1,000.00 " "$1,000.00 " "$1,000.00 " "$2,600.00 " "$2,600.00 “ # no
>>>  change. Why?
>>>
>>>>  gsub(".00", "", y)  # note: that’s dot zero zero, replace with “"
>>>>
>>>  [1] "$10 " "$10 " "$10 " "$2, " "$2, “  #WTF?
>>>
>>>  I’ve also tried sapply and apply, but haven’t yet tried a loop. (These
>>>  were done in desperation; gsub ought to work the way the help says.) I’ve
>>>  tried lots more than is listed here, over and over, with no results. I’d be
>>>  grateful for any guidance you can provide.
>>>
>>>  Thanks in advance,
>>>
>>>  Jim Plante
>>>
>>> ------------------------------
>>>
>>>  R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>>  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.
>>>
>>
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>>
>> ------------------------------
>>
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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.
>>
>>

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