[R] Identifying columns with specific character

[Rui Barradas]

Hello,

To the OP:
The dollar sign is a meta character, so it must be escaped, that is what 
was wrong with your code. The right regular expression would be

grepl("\\$", x)

When a regular expression doesn't work, try reading the help page ?regex.

Another good source you can try is

https://regex101.com


Hope this helps,

Rui Barradas

On 4/18/2018 11:19 PM, Jim Lemon wrote:
> Hi Farnoosh,
> Perhaps this will help:
> 
> drop_dollar<-function(x) return(as.numeric(as.character(gsub("\\$","",x))))
> sapply(My.Data,drop_dollar)
> 
> Jim
> 
> On Thu, Apr 19, 2018 at 7:23 AM, Farnoosh Sheikhi via R-help
> <r-help using r-project.org> wrote:
>> Hello,
>> I have a data frame with 400 columns and wanted to filter character columns with "$" in it.For example: >  x <- c("$5", "$89", "$10", "$34")  >  y <- c(1:4)>  My.Data <- data.frame (x,y)> My.Data    x y1  $5 12 $89 23 $10 34 $34 4
>> I want to detect the columns with $ and remove the $ from the selected columns.I have tried apply(My.Data, 2, function (x) any(grepl("$", x))) but it's not really working.Or:  apply(My.Data, 2, function(x){x<-gsub("\\$", "", x)}) works but it turns all the columns to a factor.
>> Thanks.
>>          [[alternative HTML version deleted]]
>>
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> 
> ______________________________________________
> R-help using 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.
>