[R] R grep & gsub issue - sign seems to be causing an issue...

[Duncan Murdoch]

Jason Rupert wrote:
> I would like to use grep and gsub to manipulate a vector to make the names used consistent, i.e. reduce a level or two.  
>   

This is dangerous:  grep and gsub use regular expressions, so a lot of 
characters (see ?regexp for the list) have special meanings.

For the kind of substitutions you want, just do things like

newlist <- tmp_test
newlist[newlist == tmp_test[2]] <- tmp_test[1]

Duncan Murdoch
> However, here is what I found when I attempted to use grep and gsub:
>    
>   
>> tmp_test<-c("House 1 Plot Plus +100","House 2 Plot Plus +100","House 3 Plot Plus -100","House 4 Plot Plus -100","House 1 Plus +100","House 2 Plus +100","House 3 Plus -100","House 4 Plus -100")
>>     
>
>   
>> gsub(tmp_test[2], tmp_test[1], tmp_test)
>>     
> [1] "House 1 Plot Plus +100" "House 2 Plot Plus +100" "House 3 Plot Plus -100" "House 4 Plot Plus -100" "House 1 Plus +100"      "House 2 Plus +100"     
> [7] "House 3 Plus -100"      "House 4 Plus -100"     
>
>   
>> grep(tmp_test[1],tmp_test)
>>     
> integer(0)
>
> However, 
>   
>> gsub(tmp_test[3], tmp_test[1], tmp_test)
>>     
> [1] "House 1 Plot Plus +100" "House 2 Plot Plus +100" "House 1 Plot Plus +100" "House 4 Plot Plus -100" "House 1 Plus +100"      "House 2 Plus +100"     
> [7] "House 3 Plus -100"      "House 4 Plus -100"
>
> Thanks for any feedback that can be provided.
>
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