R help - Feb 2011 - extract printed value from a function

Hello all,

This shouldn't be difficult, but I am not able to extract a printed
value from a function and assign it to an object.

In my case,
> library(DAAG)
> twotPermutation(c(2,3,4),c(3,6,5),plotit=F)
[1] 0.298

I would like to assign this result to an object.

Thanks,

Duarte

On 2011-02-24 03:26, Duarte Viana wrote:
> Hello all,
>
> This shouldn't be difficult, but I am not able to extract a printed
> value from a function and assign it to an object.
>
> In my case,
>
>> library(DAAG)
>> twotPermutation(c(2,3,4),c(3,6,5),plotit=F)
> [1] 0.298
>
> I would like to assign this result to an object.
Two suggestions:
1.
Modify the code for twotPermutation by removing the invisible()
at the end.

2.
Use capture.output to capture the result and then convert
to numeric:

  pvstring <- capture.output(
      twotPermutation( c(2,3,4), c(3,6,5), plotit=FALSE) ))

Now you can use strsplit or substr to extract the numeric part:

  pv <- as.numeric(strsplit(pvstring, " ")[[1]][2])

or

  pv <- as.numeric(
       substr(pvstring, nchar(pvstring) - 5, nchar(pvstring)))

Peter Ehlers
>
> Thanks,
>
> Duarte
>
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