[R] grep for asterisks "*"'s

[Tony Breyal]

Hi Robin!

Does the following produce what you want mate?

### R START ###
> text <- 'this sentence contains an * (i.e. an astrix).'
> grep('\\*', text)
[1] 1
### R END ###

Regards,
Tony Breyal

On 23 Nov, 08:41, Robin Clark <robalexcl... at hotmail.com> wrote:
> Hello,
> I'm trying to determine if a string contains asterisks using the grep
> function. I know that this is slightly difficult because * is a special
> character in regular expressions and needs to be escaped. However, escaping
> the * using \ doesn't work either:
>
> if(grep("\*", model)>0) #does the model have an interaction
> {
>    do something...
>
> }
>
> produces the following error message:
>
> Error in grep("*", model) : invalid regular expression '*'
> In addition: Warning messages:
> 1: '\*' is an unrecognized escape in a character string
> 2: unrecognized escape removed from "\*"
> 3: In grep("*", model) :
>   regcomp error:  'Invalid preceding regular expression'
> Execution halted
>
> Any ideas anyone?
> Robin
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