[Rcpp-devel] regular expression in Rcpp

[Mark Leeds]

Thanks Matt and Dirk. Both suggestions are good. I'll try one of them ( not
sure which
yet ) and let you know how it works out. Definitely it's not as as easy a
problem as I originally thought. Thanks again.


Mark

On Tue, Jan 13, 2015 at 9:41 AM, Matt D. <matdzb at gmail.com> wrote:

> On 1/13/2015 07:27, Mark Leeds wrote:
>
>> Hi All: I was trying to do something with regular expressions in Rcpp so
>> I piggy backed
>> heavily off of Dirk's boost.regex example in the Rcpp Gallery where he
>> takes streams of digits and checks them for machine and human readability.
>>
> Hi!
>
>>
>> My problem is actually pretty different and simpler. Essentially, if a
>> character string ends in "rhofixed" or "norhofixed", then that part of the
>> character string should be removed. The R code below illiustrates what I'm
>> trying to do.
>>
>> But, when I write the Rcpp code to do the same thing and  set
>> Sys.setenv("PKG_LIBS"="-lboost_regex"), I don't get the same result. I
>> don't know if  it's due to the regex engine being different in boost or I
>> could be doing something else wrong. Thanks for any help.
>>
> It does indeed seems simpler than an usual use case for regex. Hence,
> perhaps you can go about it differently:
> - use `boost::algorithm::ends_with` (from <boost/algorithm/string/predicate.hpp>)
> to check whether your predicate (i.e., a character string ends in
> "rhofixed" or "norhofixed") holds
> - if so, use the `erase` member function (http://en.cppreference.com/w/
> cpp/string/basic_string/substr) to get rid of the substring (note: if one
> of the aforementioned predicates is satisfied, then you can trivially infer
> how long is the substring subject to removal -- and can thus use, say, the
> iterator-pair version, stepping backward from `std::end(your_string)` as
> needed).
>
> HTH!
>
> Best,
>
> Matt
>
>
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