Help with stemDocument

Le jeudi 10 mai 2012 ? 17:12 -0700, Triss.Ashton a ?crit :

Alekseiy, I tried your recommendation with several variations. It still
does
not run.  I think the problem has to do with R2.15 and the refreshed TM
package.

It works here with R 2.15.0 and tm 0.5-7.2 (development version), all
other relevant packages of the same version as you (but on Linux 64
bits). So it might not be the problem.

I'm using the docs example as a test:
data("crude")
crude[[1]]
stemDocument(crude[[1]])

Everything runs under R2.10 with the following code:

a <- Corpus(VectorSource(df$text)) # create corpus object
a <- tm_map(a, removePunctuation)
a <- tm_map(a, removeNumbers)
a <- tm_map(a, removeWords, stopwords("english"))
a <- tm_map(a, stripWhitespace)		
a <- tm_map(a, stemDocument, language = "english") 

Let's focus on the example from the docs, since it's simple. Anyway, you
example is not reproducible since you do not provide the original data.

This same code ran on R2.15 results in:
1. the removeWords working sometimes, and sometimes not.
2. and stemDocuments absolutely not working.  

Both error out.  removeWords always stops reading in the stopword list on
the same line number  (I have added and subtracted words - no difference)
-
session info is below:

a <- tm_map(a, removeWords, stopwords("english"))

Error in gsub(sprintf("\\b(%s)\\b", paste(words, collapse = "|")), "",  : 
  invalid regular expression
'\b(a|about|above|across|after|again|against|all|almost|alone|along|already|also|although|always|am|among|an|and|another|any|anybody|anyone|anything|anywhere|are|area|areas|aren't|around|as|ask|asked|asking|asks|at|away|b|back|backed|backing|backs|be|became|because|become|becomes|been|before|began|behind|being|beings|below|best|better|between|big|both|but|by|c|came|can|cannot|can't|case|cases|certain|certainly|clear|clearly|come|could|couldn't|d|did|didn't|differ|different|differently|do|does|doesn't|doing|done|don't|down|downed|downing|downs|during|e|each|early|either|end|ended|ending|ends|enough|even|evenly|ever|every|everybody|everyone|everything|everywhere|f|face|faces|fact|facts|far|felt|few|find|finds|first|for|four|from|full|fully|further|furthered|furthering|furthers|g|gave|general|generally|get|gets|give|given|gives|go|going|good|goods|got|great|greater|greatest|group|grouped|grouping|groups|h|had|hadn't|has|hasn't|have|haven't|having|he|he

a <- tm_map(a, stemDocument, language = "english") 

Error in .jnew(name) : java.lang.ClassNotFoundException

This error suggests you should reconfigure Java. Have you tried
reinstalling rJava, Snowball, RWekajars and RWeka?

SessionInfo:

sessionInfo()

R version 2.15.0 (2012-03-30)
Platform: i386-pc-mingw32/i386 (32-bit)

locale:
[1] LC_COLLATE=English_United States.1252 
[2] LC_CTYPE=English_United States.1252   
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C                          
[5] LC_TIME=English_United States.1252    

attached base packages:
[1] stats4    grid      stats     graphics  grDevices utils     datasets 
[8] methods   base     

other attached packages:
 [1] topicmodels_0.1-5 slam_0.1-23       modeltools_0.2-19 lasso2_1.2-12    
 [5] pvclust_1.2-2     stringr_0.6       plyr_1.7.1        Snowball_0.0-8   
 [9] rJava_0.9-3       ggplot2_0.9.0     tm_0.5-7.1       
twitteR_0.99.19  
[13] rjson_0.2.8       RCurl_1.91-1.1    bitops_1.0-4.1   

loaded via a namespace (and not attached):
 [1] colorspace_1.1-1   dichromat_1.2-4    digest_0.5.2       MASS_7.3-17       
 [5] memoise_0.1        munsell_0.3        proto_0.3-9.2     
RColorBrewer_1.0-5
 [9] reshape2_1.2.1     RWeka_0.4-11       RWekajars_3.7.5-1 
scales_0.2.0      

Hi Triss, 

If you need to stem just one text in the Corupus use a[[n]]<-stemDocument

Best,
-Alex