[R] suggestion of regex pattern

[Boris Steipe]

Re-reading your question and taking a wild guess, perhaps you are looking for parse() and eval() ...

xyz <- data.frame( a=c(1,2), b=c(3,4))
xyz

  a b
1 1 3
2 2 4

expp <- parse(text="xyz$a > 1 & xyz$b == 4")   # turn a string into an expression
expp

expression(xyz$a > 1 & xyz$b == 4)

xyz[eval(expp), ]                              # evaluate an expression in place
  a b
2 2 4

... but really, it's just a guess at what you might be trying to do.

B.



 
On Apr 18, 2015, at 1:30 PM, Boris Steipe <boris.steipe at utoronto.ca> wrote:

> Sorry - it's not entirely clear to me what you need to do.
> 
> See here for some hints on how to ask questions on this list. I'm sure we'll be able to help quickly.
> http://adv-r.had.co.nz/Reproducibility.html
> http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
> (and don't post in HTML   :-)
> 
> 
> B.
> 
> On Apr 18, 2015, at 11:10 AM, Fernando Gama <f.fabiogama88 at gmail.com> wrote:
> 
>> Hello Boris,
>> 
>> thanks for your response. 
>> 
>> So, firstly considered that  i've been input a set of serches strings (.txt format) and i'm using regex to transform in a suitable  format to my script. This part is a final part of my code and i wish putting in input to a subset.
>> 
>> (.txt formatted)
>> 
>> ---- STRINGS (INPUT)
>> 
>> [1]  "municipio =='Limeira' "
>> [2]  "municipio =='Limeira' & mesincident =='marco' "
>> [3]  "​municipio =='Limeira' & mesincident =='marco' & trechoklmetros > 1.00 12.300"
>> ...
>> ..
>> ..
>> ..
>> [n] "......"
>> 
>> --------------
>> 
>> desired_fomart <- ​it will reveice all strings to filter in a dataset by subset below:
>> 
>> 
>> a loop each line:
>> 
>> subset(dataset_read, desired_fomart[i])
>> 
>> My question: taking into consideration this cenario, in your oppinion your reply is my suitable for my problem, whereas i will to map each value in database?
>> 
>> Once again, thank so much! :)
>> 
>> 2015-04-18 11:04 GMT-03:00 Boris Steipe <boris.steipe at utoronto.ca>:
>> This is not a regular expression but simply a conjunction (sequence of '&') of logical expressions. Moreover it's not wrong. Consider:
>> 
>> xyz <- data.frame(municipio = c('Limeira'), mesincident = c('marco'), trechoklmetros = c(3.00, -4.00, 30))
>> xyz
>> 
>>  municipio mesincident trechoklmetros
>> 1   Limeira       marco              3
>> 2   Limeira       marco             -4
>> 3   Limeira       marco             30
>> 
>> 
>> xyz$municipio =='Limeira' & xyz$mesincident =='marco' & xyz$trechoklmetros > 1.00
>> [1]  TRUE FALSE  TRUE
>> 
>> xyz$municipio =='Limeira' & xyz$mesincident =='marco' & xyz$trechoklmetros > 1.00 & xyz$trechoklmetros <= 12.3
>> [1]  TRUE FALSE FALSE
>> 
>> 
>> If there's a problem it seems to be elsewhere.
>> Cheers,
>> Boris
>> 
>> 
>> On Apr 17, 2015, at 4:22 PM, Fernando Gama <f.fabiogama88 at gmail.com> wrote:
>> 
>>> Hello,
>>> 
>>> I have benn problems to construct the pattern for this:
>>> 
>>> municipio =='Limeira' & mesincident =='marco' & trechoklmetros > 1.00 12.300
>>> 
>>> I would like:
>>> 
>>> municipio =='Limeira' & mesincident =='marco' & trechoklmetros > 1.00
>>> *& **trechoklmetros
>>> <= *12.300
>>> ​
>>> ​Any suggestion?​
>>> 
>>> 
>>> --
>>> Att,
>>> 
>>> Fernando Gama da Mata
>>> 
>>>      [[alternative HTML version deleted]]
>>> 
>>> ______________________________________________
>>> 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.
>> 
>> 
>> 
>> 
>> -- 
>> Att,
>> 
>> Fernando Gama da Mata
>> 
>> 
> 
> ______________________________________________
> 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.