[R] stringr package question

[Jeff Newmiller]

Seems more likely to be related to changes in the options stringr uses 
when it invokes the regex code? See the different response coming from 
base R when told to use a different regex engine:

> grep( "+proj", "syz+project" )
[1] 1
> grep( "+proj", "syz+project", perl=TRUE )
Error in grep("+proj", "syz+project", perl = TRUE) :
   invalid regular expression '+proj'
In addition: Warning message:
In grep("+proj", "syz+project", perl = TRUE) :
   PCRE pattern compilation error
         'nothing to repeat'
         at '+proj'

On Thu, 13 Aug 2015, Mauricio Romero wrote:

> thanks.... that makes sense... in the previous version of R it worked for
> some reason.
>
> On Thu, Aug 13, 2015 at 4:33 PM, Sarah Goslee <sarah.goslee at gmail.com>
> wrote:
>
>> Hi,
>>
>> The + is a special character in regular expressions. If you want to
>> match a literal + you need to escape it:
>>
>> str_extract("+proj=utm +zone=19 +datum=WGS84 +units=m +no_defs
>> +ellps=WGS84 +towgs84=0,0,0", "\\+proj=[a-zA-Z0-9]*")
>>
>> Sarah
>>
>>
>> On Thu, Aug 13, 2015 at 2:55 PM, Mauricio Romero
>> <mauricioromerolondono at gmail.com> wrote:
>>> Hi,
>>>
>>> I'm running R 3.2.1 and im having an unexpected problem... when I run the
>>> follwing code it returns an error
>>>
>>> library(stringr)
>>> str_extract("+proj=utm +zone=19 +datum=WGS84 +units=m +no_defs
>> +ellps=WGS84
>>> +towgs84=0,0,0", "+proj=[a-zA-Z0-9]*")
>>>
>>> But I can't find whats wrong with my code.
>>>
>>> Thanks
>>>
>>> Mauricio
>>>
>>
>
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>
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