[R] RegExp question

[Andrej]

Thanks David for your fast reply, but now I realized tat "string" is
of type:

> class(string)
[1] "jobjRef"
attr(,"package")
[1] "rJava"

so I get an error when i try with gsub or sub:

> sub("^.+\\t(\\d+)\\n.+$", "\\1", string)
Error in as.character.default(x) :
  no method for coercing this S4 class to a vector

I think that there should be trivial solution, but... Any further
idea?

Regards, Andrej



On Jun 16, 6:47 pm, David Winsemius <dwinsem... at comcast.net> wrote:
> On Jun 16, 2010, at 12:04 PM, Andrej wrote:
>
> > Dear all,
>
> > I'm trying to filter out the "number of leaves" (it should be 1 in the
> > example below) from the following string:
>
> >> string
> > [1] "Java-Object{J48 pruned tree\n------------------\n: 0 (15.0/3.0)\n
> > \nNumber of Leaves  : \t1\n\nSize of the tree : \t1\n}"
>
> > Any idea how to do that as simple as possible? Thanks in advance for
> > any advice.
>
> ?sub   # or ?gsub if you need more than one pattern matched (they are  
> on the same page).
>
> This should find the first occurrence of digits following a tab  
> terminated by a line feed and then return only the digits:
>
> string <- "Java-Object{J48 pruned tree\n------------------\n: 0  
> (15.0/3.0)\n \nNumber of Leaves  : \t1\n\nSize of the tree : \t1\n}"
> sub("^.+\\t(\\d+)\\n.+$", "\\1", string)
> [1] "1"
>
> The parens within the search pattern are matched to "\\1". Need to  
> double backslashed within patterns.
>
>
>
> > Regards, Andrej
>
> --
>
> David Winsemius, MD
> West Hartford, CT
>
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