I have been breaking my head over this one over the last few days. I searched all the SO archives and tried the suggested solutions but just can't seem to get this to work. I have sets of txt documents in folders such as 2000 06, 1995 -99 etc, and want to run some basic text mining operations such as creating document term matrix and term document matrix and doing some operations based co-locations of words. My script works on a smaller corpus, however, when I try it with the bigger corpus, it fails me. I have pasted in the code for one such folder operation.
library(tm) # Framework for text mining.
library(SnowballC) # Provides wordStem() for stemming.
library(RColorBrewer) # Generate palette of colours for plots.
library(ggplot2) # Plot word frequencies.
library(magrittr)
library(Rgraphviz)
library(directlabels)
setwd("/ConvertedText")
txt <- file.path("2000 -06")
docs<-VCorpus(DirSource(txt, encoding = "UTF-8"),readerControl = list(language = "UTF-8"))
docs <- tm_map(docs, content_transformer(tolower), mc.cores=1)
docs <- tm_map(docs, removeNumbers, mc.cores=1)
docs <- tm_map(docs, removePunctuation, mc.cores=1)
docs <- tm_map(docs, stripWhitespace, mc.cores=1)
docs <- tm_map(docs, removeWords, stopwords("SMART"), mc.cores=1)
docs <- tm_map(docs, removeWords, stopwords("en"), mc.cores=1)
#corpus creation complete
setwd("/ConvertedText/output")
dtm<-DocumentTermMatrix(docs)
tdm<-TermDocumentMatrix(docs)
m<-as.matrix(dtm)
write.csv(m, file="dtm.csv")
dtms<-removeSparseTerms(dtm, 0.2)
m1<-as.matrix(dtms)
write.csv(m1, file="dtms.csv")
# matrix creation/storage complete
freq <- sort(colSums(as.matrix(dtm)), decreasing=TRUE)
wf <- data.frame(word=names(freq), freq=freq)
freq[1:50]
#adjust freq score in next line
p <- ggplot(subset(wf, freq>100), aes(word, freq))+ geom_bar(stat="identity")+ theme(axis.text.x=element_text(angle=45, hjust=1))
ggsave("frequency2000-06.png", height=12,width=17, dpi=72)
# frequency graph generated
x<-as.matrix(findFreqTerms(dtm, lowfreq=1000))
write.csv(x, file="freqterms00-06.csv")
png("correlation2000-06.png", width=12, height=12, units="in", res=900)
graph.par(list(edges=list(col="lightblue", lty="solid", lwd=0.3)))
graph.par(list(nodes=list(col="darkgreen", lty="dotted", lwd=2, fontsize=50)))
plot(dtm, terms=findFreqTerms(dtm, lowfreq=1000)[1:50],corThreshold=0.7)
dev.off()
When I use the mc.cores=1 argument in tm_map, the operation continues indefinitely. However, if I use the lazy=TRUE argument in tm_map, it seemingly goes well, but subsequent operations give this error.
Error in UseMethod("meta", x) :
no applicable method for 'meta' applied to an object of class "try-error"
In addition: Warning messages:
1: In mclapply(x$content[i], function(d) tm_reduce(d, x$lazy$maps)) :
all scheduled cores encountered errors in user code
2: In mclapply(unname(content(x)), termFreq, control) :
all scheduled cores encountered errors in user code
I have been looking all over for a solution but have failed consistently. Any help would be greatly appreciated!
Best! k