Re: [R] find a sequence of characters in a vector
I think I would use Sundar's solution but here are a couple
more just in case:
> x <- c("a", "z", "e")
> y <- c("a", "z", "e", "r", "t", "a", "z", "a", "z", "e", "c")
>
> #1
> which(apply(embed(y, 3), 1, identical, rev(x)))
[1] 1 8
> #2
> library(zoo)
> which(rollapply(zoo(y), 3, identical, x, align = "left"))
[1] 1 8
On Fri, Jun 5, 2009 at 9:30 AM, Sundar Dorai-Raj wrote:
> use gregexpr and paste
>
>> aze <- paste(c("a", "z", "e"), collapse = "")
>> sequence <- paste(c("a","z","e","r","t","a","z","a","z","e","c"), collapse =
>> "")
>> gregexpr(aze, sequence, fixed = TRUE)
> [[1]]
> [1] 1 8
> attr(,"match.length")
> [1] 3 3
>
> HTH,
>
> --sundar
>
> On Fri, Jun 5, 2009 at 6:22 AM, Ptit_Bleu wrote:
>>
>> Hello,
>>
>> I'm just looking for an easy way to find the positions of a complete
>> sequence in a bigger vector.
>> For example :
>> c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c")
>> and the result should be
>> 1 8
>> that is the positions of the beginning of the complete sequence.
>>
>> I tried with %in%, match, is.element but all I get is, for example
>> which(c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c"))
>> 1 2 3
>> meaning that each character is in the bigger vector.
>>
>> It must be easy, except for me. Sorry.
>>
>> If you have a solution, thanks in advance to share it.
>> Have a good week-end,
>> Ptit Bleu.
>>
>> --
>> View this message in context:
>> http://www.nabble.com/find-a-sequence-of-characters-in-a-vector-tp23888063p23888063.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> __
>> R-help@r-project.org mailing list
>> 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.
>>
>
> __
> R-help@r-project.org mailing list
> 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.
>
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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Re: [R] find a sequence of characters in a vector
Here is one approach (this could be wrapped into a function if you are applying
it repeatedly):
> one <- c("a","z","e")
> two <- c("a","z","e","r","t","a","z","a","z","e","c")
>
> which( sapply( 1:(length(two)-length(one)+1),
+ function(i) isTRUE( all.equal( one, two[ i + 0:(length(one)-1) ] ) ) ) )
[1] 1 8
>
Hope this helps,
--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.s...@imail.org
801.408.8111
> -Original Message-
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
> project.org] On Behalf Of Ptit_Bleu
> Sent: Friday, June 05, 2009 7:22 AM
> To: r-help@r-project.org
> Subject: [R] find a sequence of characters in a vector
>
>
> Hello,
>
> I'm just looking for an easy way to find the positions of a complete
> sequence in a bigger vector.
> For example :
> c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c")
> and the result should be
> 1 8
> that is the positions of the beginning of the complete sequence.
>
> I tried with %in%, match, is.element but all I get is, for example
> which(c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c"))
> 1 2 3
> meaning that each character is in the bigger vector.
>
> It must be easy, except for me. Sorry.
>
> If you have a solution, thanks in advance to share it.
> Have a good week-end,
> Ptit Bleu.
>
> --
> View this message in context: http://www.nabble.com/find-a-sequence-of-
> characters-in-a-vector-tp23888063p23888063.html
> Sent from the R help mailing list archive at Nabble.com.
>
> __
> R-help@r-project.org mailing list
> 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.
__
R-help@r-project.org mailing list
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.
Re: [R] find a sequence of characters in a vector
use gregexpr and paste
> aze <- paste(c("a", "z", "e"), collapse = "")
> sequence <- paste(c("a","z","e","r","t","a","z","a","z","e","c"), collapse =
> "")
> gregexpr(aze, sequence, fixed = TRUE)
[[1]]
[1] 1 8
attr(,"match.length")
[1] 3 3
HTH,
--sundar
On Fri, Jun 5, 2009 at 6:22 AM, Ptit_Bleu wrote:
>
> Hello,
>
> I'm just looking for an easy way to find the positions of a complete
> sequence in a bigger vector.
> For example :
> c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c")
> and the result should be
> 1 8
> that is the positions of the beginning of the complete sequence.
>
> I tried with %in%, match, is.element but all I get is, for example
> which(c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c"))
> 1 2 3
> meaning that each character is in the bigger vector.
>
> It must be easy, except for me. Sorry.
>
> If you have a solution, thanks in advance to share it.
> Have a good week-end,
> Ptit Bleu.
>
> --
> View this message in context:
> http://www.nabble.com/find-a-sequence-of-characters-in-a-vector-tp23888063p23888063.html
> Sent from the R help mailing list archive at Nabble.com.
>
> __
> R-help@r-project.org mailing list
> 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.
>
__
R-help@r-project.org mailing list
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.
[R] find a sequence of characters in a vector
Hello,
I'm just looking for an easy way to find the positions of a complete
sequence in a bigger vector.
For example :
c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c")
and the result should be
1 8
that is the positions of the beginning of the complete sequence.
I tried with %in%, match, is.element but all I get is, for example
which(c("a","z","e") in c("a","z","e","r","t","a","z","a","z","e","c"))
1 2 3
meaning that each character is in the bigger vector.
It must be easy, except for me. Sorry.
If you have a solution, thanks in advance to share it.
Have a good week-end,
Ptit Bleu.
--
View this message in context:
http://www.nabble.com/find-a-sequence-of-characters-in-a-vector-tp23888063p23888063.html
Sent from the R help mailing list archive at Nabble.com.
__
R-help@r-project.org mailing list
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.
