Document term matrix in R - r

Question

I have the following code:
rm(list=ls(all=TRUE)) #clear data
setwd("~/UCSB/14 Win 15/Issy/text.fwt") #set working directory
files <- list.files(); head(files) #load & check working directory
fw1 <- scan(what="c", sep="\n",file="fw_chp01.fwt")
library(tm)
corpus2<-Corpus(VectorSource(c(fw1)))
skipWords<-(function(x) removeWords(x, stopwords("english")))
#remove punc, numbers, stopwords, etc
funcs<-list(content_transformer(tolower), removePunctuation, removeNumbers, stripWhitespace, skipWords)
corpus2.proc<-tm_map(corpus2, FUN = tm_reduce, tmFuns = funcs)
corpus2a.dtm <- DocumentTermMatrix(corpus2.proc, control = list(wordLengths = c(1,110))) #create document term matrix
I'm trying use some of the operations detailed in the tm reference manual (http://cran.r-project.org/web/packages/tm/tm.pdf) with little success. For example, when I try to use the findFreqTerms, I get the following error:
Error: inherits(x, c("DocumentTermMatrix", "TermDocumentMatrix")) is not TRUE
Can anyone clue me in as to why this isn't working and what I can do to fix it?
Edited for #lawyeR:
head(fw1) produces the first six lines of the text (Episode 1 of Finnegans Wake by James Joyce):
[1] "003.01 riverrun, past Eve and Adam's, from swerve of shore to bend"
[2] "003.02 of bay, brings us by a commodius vicus of recirculation back to"
[3] "003.03 Howth Castle and Environs."
[4] "003.04 Sir Tristram, violer d'amores, fr'over the short sea, had passen-"
[5] "003.05 core rearrived from North Armorica on this side the scraggy"
[6] "003.06 isthmus of Europe Minor to wielderfight his penisolate war: nor"
inspect(corpus2) outputs each line of the text in the following format (this is the final line of the text):
[[960]]
<<PlainTextDocument (metadata: 7)>>
029.36 borough. #this part differs by line of course
inspect(corpus2a.dtm) returns a table of all the types (there are 4163 in total( in the text in the following format:
Docs youths yoxen yu yurap yutah zee zephiroth zine zingzang zmorde zoom
1 0 0 0 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 0 0 0 0 0

Answer 1

Here is a simplified form of what you provided and did, and tm does its job. It may be that one or more of your cleaning steps caused a problem.
> library(tm)
> fw1 <- c("riverrun, past Eve and Adam's, from swerve of shore to bend
+ of bay, brings us by a commodius vicus of recirculation back to
+ Howth Castle and Environs.
+ Sir Tristram, violer d'amores, fr'over the short sea, had passen-
+ core rearrived from North Armorica on this side the scraggy
+ isthmus of Europe Minor to wielderfight his penisolate war: nor")
>
> corpus<-Corpus(VectorSource(c(fw1)))
> inspect(corpus)
<<VCorpus (documents: 1, metadata (corpus/indexed): 0/0)>>
[[1]]
<<PlainTextDocument (metadata: 7)>>
riverrun, past Eve and Adam's, from swerve of shore to bend
of bay, brings us by a commodius vicus of recirculation back to
Howth Castle and Environs.
Sir Tristram, violer d'amores, fr'over the short sea, had passen-
core rearrived from North Armorica on this side the scraggy
isthmus of Europe Minor to wielderfight his penisolate war: nor
> dtm <- DocumentTermMatrix(corpus)
> findFreqTerms(dtm)
[1] "adam's," "and" "armorica" "back" "bay," "bend"
[7] "brings" "castle" "commodius" "core" "d'amores," "environs."
[13] "europe" "eve" "fr'over" "from" "had" "his"
[19] "howth" "isthmus" "minor" "nor" "north" "passen-"
[25] "past" "penisolate" "rearrived" "recirculation" "riverrun," "scraggy"
[31] "sea," "shore" "short" "side" "sir" "swerve"
[37] "the" "this" "tristram," "vicus" "violer" "war:"
[43] "wielderfight"
As another point, I find it useful at the start to load a few other complementary packages to tm.
library(SnowballC); library(RWeka); library(rJava); library(RWekajars)
For what its worth, as compared to your somewhat complicated cleaning steps, I usually trudge along like this (replace comments$comment with your text vector):
comments$comment <- tolower(comments$comment)
comments$comment <- removeNumbers(comments$comment)
comments$comment <- stripWhitespace(comments$comment)
comments$comment <- str_replace_all(comments$comment, " ", " ")
# replace all double spaces internally with single space
# better to remove punctuation with str_ because the tm function doesn't insert a space
library(stringr)
comments$comment <- str_replace_all(comments$comment, pattern = "[[:punct:]]", " ")
comments$comment <- removeWords(comments$comment, stopwords(kind = "english"))

Answer 2

From another ticket this should help tm 0.6.0 has a bug and it can be addressed with this statement.
corpus_clean <- tm_map( corp_stemmed, PlainTextDocument)
Hope this helps.