I have narrowed the problem down to this:
NGramTokenizer("-", control = Weka_control(min = 1, max = 4))
The string actually occurs as fourth segment in the 21,226th sentence. I find
this strange, since I am
using the default delimiters ' \r\n\t.,;:'"()?!', which do not contain a hyphen.
Regards,
Richard
On Tue, 12 Jan 2010 16:50:16 +0100, Richard R. Liu wrote
> I am running R version 2.10.1 Patched (2010-01-07 r50940) in 64-bit
> mode under Mac OS X 10.5.8 on a MacBook Pro with 8GB RAM.
>
> I am encountering the following error in RWeka:
>
> Error in .jcall("weka/core/tokenizers/Tokenizer", "[S", "tokenize",
> .jcast(tokenizer, : java.lang.StringIndexOutOfBoundsException:
> String index out of range: 1
>
> Here is the code that is causing the problem:
>
> > library(rJava)
> > (.jinit(parameters = "-Xmx3000m"))
> > library(RWeka)
> > wctrl <- Weka_control(min = 1, max = 4)
> > lseg.4gram <- lapply(lseg, NGramTokenizer, control = wctrl)
>
> lseg is a list of 965193 sentences, each of which consists of one or
> more segments. For example, lseg[[1]] is
>
> [[1]]
> [1] "calculation of results xxxx activity is defined as the increase
> in radioactivity " [2] "in dpm"
> [3] "in the pellet "
> [4] "xxx"
>
> [5] ""
> [6] "caused by the addition of xx xxxx"
>
> lapply should build 1-, 2-, 3- and 4-grams of each sentence segment.
> Is there any way to solve or circumvent the error? In Java
> Preferences on the Mac I have specified for applications Java SE 6
> 64- bit, then J2SE 5.0 64-bit, before other 32-bit versions.
>
> (Side remark: I'm surprised that it only does this for the first
> and last segments of the first sentence. Admittedly, the other
> segments have less than 4 grams, but that should not stop it from
> building n- grams consisting of fewer grams!)
>
> Thanks,
> Richard
> ------
> Richard R. Liu
> Dittingerstr. 33
> CH-4053 Basel
> Switzerland
>
> Tel.: +41 61 331 10 47
> Email: richard....@pueo-owl.ch
--
Richard R. Liu
Dittingerstr. 33
CH-4053 Basel
Switzerland
Tel.: +41 61 331 10 47
Email: richard....@pueo-owl.ch
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