TL;DR:
library(tm)
library(wordcloud)
mytextFile <- "sba.txt"
mytext <- scan(mytextFile, character(0), sep="\n")
words.vec <- VectorSource(mytext)
words.corpus <- Corpus(words.vec)
words.corpus <- tm_map(words.corpus, content_transformer(tolower))
words.corpus <- tm_map(words.corpus, removePunctuation)
words.corpus <- tm_map(words.corpus, removeWords, stopwords("english"))
tdm <- TermDocumentMatrix(words.corpus)
m <- as.matrix(tdm)
wordCounts <- rowSums(m)
wordCounts <- sort(wordCounts, decreasing=TRUE)
cloudFrame <- data.frame(word=names(wordCounts),freq=wordCounts)
wordcloud(cloudFrame$word, cloudFrame$freq)
