Trying to use pipes in R

[Julio Sergio Santana]

Hi,
I'm trying to use pipes in R. By now, I could launch the linux command "wc"
(to count words from a text), but
I don't know how to capture the results, say in a vector of chars...
Here is the R code I'm trying:

:> f <- pipe("wc", open="w")
:> writeLines(c("uno dos tres", "cuatro cinco", "seis"), f)
:> close(f)
:     3       6      31

The result is just displayed but I couldn't put the result into a R
variable.
Do you have any comments on this?

Thanks,
-- Sergio.

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[arun kirshna]

Hi,

If you want to just count the words in R, try this:
vec1<-c("uno dos tres", "cuatro cinco", "seis")
#get individual word count within quotes
res1<-unlist(lapply(strsplit(vec1, " "),length))
res1
#[1] 3 2 1

#get whole word count
length(unlist(strsplit(vec1, " ")))
#[1] 6





----- Original Message -----
From: Julio Sergio Santana <[hidden email]>
To: [hidden email]
Cc:
Sent: Wednesday, September 12, 2012 1:40 PM
Subject: [R] Trying to use pipes in R

Hi,
I'm trying to use pipes in R. By now, I could launch the linux command "wc"
(to count words from a text), but
I don't know how to capture the results, say in a vector of chars...
Here is the R code I'm trying:

:> f <- pipe("wc", open="w")
:> writeLines(c("uno dos tres", "cuatro cinco", "seis"), f)
:> close(f)
:     3       6      31

The result is just displayed but I couldn't put the result into a R
variable.
Do you have any comments on this?

Thanks,
-- Sergio.

    [[alternative HTML version deleted]]

______________________________________________
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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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[Julio Sergio Santana]

No, this is not what I want, "wc" is just an example. What I want is to
shut a process to do a task outside R, and to
get its results back in R



On Wed, Sep 12, 2012 at 1:07 PM, arun <[hidden email]> wrote:

> Hi,
>
> If you want to just count the words in R, try this:
> vec1<-c("uno dos tres", "cuatro cinco", "seis")
> #get individual word count within quotes
> res1<-unlist(lapply(strsplit(vec1, " "),length))
> res1
> #[1] 3 2 1
>
> #get whole word count
> length(unlist(strsplit(vec1, " ")))
> #[1] 6
>
>
>
>
>
> ----- Original Message -----
> From: Julio Sergio Santana <[hidden email]>
> To: [hidden email]
> Cc:
> Sent: Wednesday, September 12, 2012 1:40 PM
> Subject: [R] Trying to use pipes in R
>
> Hi,
> I'm trying to use pipes in R. By now, I could launch the linux command "wc"
> (to count words from a text), but
> I don't know how to capture the results, say in a vector of chars...
> Here is the R code I'm trying:
>
> :> f <- pipe("wc", open="w")
> :> writeLines(c("uno dos tres", "cuatro cinco", "seis"), f)
> :> close(f)
> :     3       6      31
>
> The result is just displayed but I couldn't put the result into a R
> variable.
> Do you have any comments on this?
>
> Thanks,
> -- Sergio.
>
>     [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] 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.
>
>

--
Julio Sergio Santana
Instituto Mexicano de Tecnología del Agua
Tel       [phone] x 826
Tel/Fax [phone]
-------------------------------------------

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[Duncan Murdoch-2]

On 12/09/2012 1:40 PM, Julio Sergio Santana wrote:

> Hi,
> I'm trying to use pipes in R. By now, I could launch the linux command "wc"
> (to count words from a text), but
> I don't know how to capture the results, say in a vector of chars...
> Here is the R code I'm trying:
>
> :> f <- pipe("wc", open="w")
> :> writeLines(c("uno dos tres", "cuatro cinco", "seis"), f)
> :> close(f)
> :     3       6      31
>
> The result is just displayed but I couldn't put the result into a R
> variable.
> Do you have any comments on this?

The examples on the page don't show R both giving input and reading
output from the same pipe.  I don't think you can set it up that way; R
is only one process.  The usual approach is what is shown there:  write
to a temporary file, then pipe the results of a command that works on
that file back into R.  I guess you could also pipe some data into a
command that writes a file, and then read that.

Duncan Murdoch

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[Petr Savicky]

On Wed, Sep 12, 2012 at 12:40:54PM -0500, Julio Sergio Santana wrote:

> Hi,
> I'm trying to use pipes in R. By now, I could launch the linux command "wc"
> (to count words from a text), but
> I don't know how to capture the results, say in a vector of chars...
> Here is the R code I'm trying:
>
> :> f <- pipe("wc", open="w")
> :> writeLines(c("uno dos tres", "cuatro cinco", "seis"), f)
> :> close(f)
> :     3       6      31
>
> The result is just displayed but I couldn't put the result into a R
> variable.
> Do you have any comments on this?

Hi.

Try the following.

  writeLines(c("uno dos tres", "cuatro cinco", "seis"), "some_file.txt")
  out <- system("wc some_file.txt", intern=TRUE)
  out

  [1] " 3  6 31 some_file.txt"

Here, out is a character variable.

Hope this helps.

Petr Savicky.

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[Julio Sergio Santana]

Thanks you all,

With your recomendations I built my solution as follows:

 :> writeLines(c("uno dos tres", "cuatro cinco", "seis"), "tempfile.txt")
 :> o <- pipe("wc < tempfile.txt", open="r")
 :> readLines(o)
 :[1] " 3  6 31"

best regards,

  --Sergio.

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[hidden email] 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.