lsa-example.R

library(lsa)

# create some sample data in temp dir
td = tempfile()
dir.create(td)
write(c("dog", "cat", "mouse"), file = paste(td, "D1", sep = "/"))
write(c("ham", "mouse", "sushi"), file = paste(td, "D2", sep = "/"))
write(c("dog", "pet", "pet"), file = paste(td, "D3", sep = "/"))

data(stopwords_en)
myMatrix0 <- textmatrix(td, stopwords = stopwords_en)
unlink(td, recursive = TRUE) # temp dir not needed anymore

# normalize using term frequency (tf) and inverse document frequency (idf)
myMatrix <- lw_logtf(myMatrix0) * gw_idf(myMatrix0)
myLSAspace <- lsa(myMatrix, dims = 2) # use just two dimensions for rendering

# plot documents in red and words in blue
plot(rbind(myLSAspace$tk, myLSAspace$dk), type = "n")
text(myLSAspace$dk, labels = rownames(myLSAspace$dk), col = "red")
text(myLSAspace$tk, labels = rownames(myLSAspace$tk), col = "blue")