R help - Jan 2012 - replacing "+" in string

I am trying to replace "+" in a string with another character 
I am getting odd results using sub and gsub
> X<-"one + two"
> gsub("+","plus",X)
[1] "plusoplusnpluseplus plus+plus
plustpluswplusoplus"
> sub("+","plus",X)
[1] "plusone + two"
> X<-"one ~ two"
it seems to work fine with other characters:
> sub("~","plus",X)
[1] "one plus two"


How do I enable "+" to be recognised as a normal character?

thanks

Nevil Amos

Two ways:

i) (If you are not using full regular expressions) Set the fixed = TRUE option.

ii) Escape it.

E.g.,

gsub("\\+", "plus", X)
gsub("+", "plus", X, fixed = TRUE)

Read up on ?regexp for an explanation of what's going on.

Michael

On Sat, Jan 21, 2012 at 2:46 PM, Nevil Amos <nevil.amos at gmail.com>
wrote:
> I am trying to replace "+" in a string with another character
> I am getting odd results using sub and gsub
>> X<-"one + two"
>> gsub("+","plus",X)
> [1] "plusoplusnpluseplus plus+plus plustpluswplusoplus"
>> sub("+","plus",X)
> [1] "plusone + two"
>> X<-"one ~ two"
>
> it seems to work fine with other characters:
>
>> sub("~","plus",X)
> [1] "one plus two"
>
>
> How do I enable "+" to be recognised as a normal character?
>
> thanks
>
> Nevil Amos
>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

+ is a metacharacter, and must be escaped:
> X <- "one + two"
> gsub("\\+", "plus", X)
[1] "one plus two"

The help for gsub() tells you to read ?regexp - that's where
the details of regular expressions as implemented in R are
explained.

Sarah

On Sat, Jan 21, 2012 at 2:46 PM, Nevil Amos <nevil.amos at gmail.com>
wrote:
> I am trying to replace "+" in a string with another character
> I am getting odd results using sub and gsub
>> X<-"one + two"
>> gsub("+","plus",X)
> [1] "plusoplusnpluseplus plus+plus plustpluswplusoplus"
>> sub("+","plus",X)
> [1] "plusone + two"
>> X<-"one ~ two"
>
> it seems to work fine with other characters:
>
>> sub("~","plus",X)
> [1] "one plus two"
>
>
> How do I enable "+" to be recognised as a normal character?
>
> thanks
>
> Nevil Amos
>

-- 
Sarah Goslee
http://www.functionaldiversity.org