R help - Apr 2007 - pattern search

Dear R-experts,

I'm looking for an easy possibility for pattern search. I have got a
string and a special pattern. I would like to know if the pattern
appears in the string, if yes where does it appear (position) and the
number of appearance.  

Example:

Text = c("If the sun shines, no clouds should be seen in the sky!")
SearchPattern = c("the")
NumberOfAppearance = 0
NumberOfLetters = 0

--> NumberOfAppearance should be 2 in the end

How can I get the string length (=number of letters stored in Text)?

Has anyone a good idea?

Thanks, Corinna

how about:

length(gregexpr("the", Text)[[1]])

?

b

On Apr 4, 2007, at 10:49 AM, Schmitt, Corinna wrote:
> Dear R-experts,
>
> I'm looking for an easy possibility for pattern search. I have got a
> string and a special pattern. I would like to know if the pattern
> appears in the string, if yes where does it appear (position) and the
> number of appearance.
>
> Example:
>
> Text = c("If the sun shines, no clouds should be seen in the
sky!")
> SearchPattern = c("the")
> NumberOfAppearance = 0
> NumberOfLetters = 0
>
> --> NumberOfAppearance should be 2 in the end
>
> How can I get the string length (=number of letters stored in Text)?
>
> Has anyone a good idea?
>
> Thanks, Corinna
>
> ______________________________________________
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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.

Hi,
> I'm looking for an easy possibility for pattern search. I have got a
> string and a special pattern. I would like to know if the pattern
> appears in the string, if yes where does it appear (position) and the
> number of appearance.  
> 
> Example:
> 
> Text = c("If the sun shines, no clouds should be seen in the
sky!")
> SearchPattern = c("the")
> NumberOfAppearance = 0
> NumberOfLetters = 0
> 
> --> NumberOfAppearance should be 2 in the end
I think you are looking for the gregexpr function.

R> Text = c("If the sun shines, no clouds should be seen in the
sky!")
R> gregexpr("the", Text)
[[1]]
[1]  4 48
attr(,"match.length")
[1] 3 3
> How can I get the string length (=number of letters stored in Text)?
Maybe the nchar funtion ?

R> nchar(Text)
[1] 55

HTH,

-- 
Julien