how to find similar sentences / phrases in R?

Question

Example, I have billions of short phrases, and I want to clusters of them that are similar.

> strings.to.cluster <- c(\"Best Toyota dealer in bay area. Dr         


        

Answer 1

You can view your phrases as "bags of words", i.e., build a matrix (a "term-document" matrix), with one row per phrase, one column per word, with 1 if the word occurs in the phrase and 0 otherwise. (You can replace 1 with some weight that would account for phrase length and word frequency). You can then apply any clustering algorithm. The tm package can help you build this matrix.

library(tm)
library(Matrix)
x <- TermDocumentMatrix( Corpus( VectorSource( strings.to.cluster ) ) )
y <- sparseMatrix( i=x$i, j=x$j, x=x$v, dimnames = dimnames(x) )  
plot( hclust(dist(t(y))) )

Answer 2

Maybe looking at this document: http://www.inside-r.org/howto/mining-twitter-airline-consumer-sentiment could help, it uses R and looks at market sentiment for airlines using twitter.