Load required libraries.

library(tm)

Set the working directory to the location of the script and data.

setwd("~/Youtube")

Load corpus from local files.

Load the Sentiment polarity dataset version 2.0 from the Movie review data.

Once unzipped, access the positive reviews in the dataset.

path = "./review_polarity/txt_sentoken/"

dir = DirSource(paste(path,"pos/",sep=""), encoding = "UTF-8")
corpus = Corpus(dir)

Check how many documents have been loaded.

length(corpus)
## [1] 1000

Take a look at the three first entries; they are not simple documents.

summary(corpus[1:3])
##                 Length Class             Mode
## cv000_29590.txt 2      PlainTextDocument list
## cv001_18431.txt 2      PlainTextDocument list
## cv002_15918.txt 2      PlainTextDocument list

Show the first entry, it can be seen that it contains the document and some metadata.

corpus[1]
## <<VCorpus (documents: 1, metadata (corpus/indexed): 0/0)>>

Access the document in the first entry.

corpus[[1]]
## <<PlainTextDocument (metadata: 7)>>
## films adapted from comic books have had plenty of success , whether they're about superheroes ( batman , superman , spawn ) , or geared toward kids ( casper ) or the arthouse crowd ( ghost world ) , but there's never really been a comic book like from hell before . 
## for starters , it was created by alan moore ( and eddie campbell ) , who brought the medium to a whole new level in the mid '80s with a 12-part series called the watchmen . 
## to say moore and campbell thoroughly researched the subject of jack the ripper would be like saying michael jackson is starting to look a little odd . 
## the book ( or " graphic novel , " if you will ) is over 500 pages long and includes nearly 30 more that consist of nothing but footnotes . 
## in other words , don't dismiss this film because of its source . 
## if you can get past the whole comic book thing , you might find another stumbling block in from hell's directors , albert and allen hughes . 
## getting the hughes brothers to direct this seems almost as ludicrous as casting carrot top in , well , anything , but riddle me this : who better to direct a film that's set in the ghetto and features really violent street crime than the mad geniuses behind menace ii society ? 
## the ghetto in question is , of course , whitechapel in 1888 london's east end . 
## it's a filthy , sooty place where the whores ( called " unfortunates " ) are starting to get a little nervous about this mysterious psychopath who has been carving through their profession with surgical precision . 
## when the first stiff turns up , copper peter godley ( robbie coltrane , the world is not enough ) calls in inspector frederick abberline ( johnny depp , blow ) to crack the case . 
## abberline , a widower , has prophetic dreams he unsuccessfully tries to quell with copious amounts of absinthe and opium . 
## upon arriving in whitechapel , he befriends an unfortunate named mary kelly ( heather graham , say it isn't so ) and proceeds to investigate the horribly gruesome crimes that even the police surgeon can't stomach . 
## i don't think anyone needs to be briefed on jack the ripper , so i won't go into the particulars here , other than to say moore and campbell have a unique and interesting theory about both the identity of the killer and the reasons he chooses to slay . 
## in the comic , they don't bother cloaking the identity of the ripper , but screenwriters terry hayes ( vertical limit ) and rafael yglesias ( les mis ? rables ) do a good job of keeping him hidden from viewers until the very end . 
## it's funny to watch the locals blindly point the finger of blame at jews and indians because , after all , an englishman could never be capable of committing such ghastly acts . 
## and from hell's ending had me whistling the stonecutters song from the simpsons for days ( " who holds back the electric car/who made steve guttenberg a star ? " ) . 
## don't worry - it'll all make sense when you see it . 
## now onto from hell's appearance : it's certainly dark and bleak enough , and it's surprising to see how much more it looks like a tim burton film than planet of the apes did ( at times , it seems like sleepy hollow 2 ) . 
## the print i saw wasn't completely finished ( both color and music had not been finalized , so no comments about marilyn manson ) , but cinematographer peter deming ( don't say a word ) ably captures the dreariness of victorian-era london and helped make the flashy killing scenes remind me of the crazy flashbacks in twin peaks , even though the violence in the film pales in comparison to that in the black-and-white comic . 
## oscar winner martin childs' ( shakespeare in love ) production design turns the original prague surroundings into one creepy place . 
## even the acting in from hell is solid , with the dreamy depp turning in a typically strong performance and deftly handling a british accent . 
## ians holm ( joe gould's secret ) and richardson ( 102 dalmatians ) log in great supporting roles , but the big surprise here is graham . 
## i cringed the first time she opened her mouth , imagining her attempt at an irish accent , but it actually wasn't half bad . 
## the film , however , is all good . 
## 2 : 00 - r for strong violence/gore , sexuality , language and drug content

Access the metadata of the first document.

meta(corpus[[1]])
## Metadata:
##   author       : character(0)
##   datetimestamp: 2015-10-18 15:01:43
##   description  : character(0)
##   heading      : character(0)
##   id           : cv000_29590.txt
##   language     : en
##   origin       : character(0)

Metadata items can also be accessed individually.

meta(corpus[[1]])$id
## [1] "cv000_29590.txt"