How to build a termdocumentmatrix in R

Question

I was wondering if it's possible to build a TermdocumentMatrix without using the package tm.

I was thinking about using two for loops in combination with a grep, but unfortunately i did not manage to create something useful.

    matrix <- matrix(, nrow=length(lvector), ncol=length(lvector))



for(i in 1:length(lvector))
{
  for(j in 1:length(l))
  {
    lijst <- grep(lvector[i],l[j])
    if (length(lijst)==0)
    {
      matrix[i,j] == 0
    }
    else 
    {
      matrix[i,j] == 1
    }

  }
}

thx in advance

Why would you want to do that? I suppose the qdap package is also off limits? — lawyeR, Mar 16 '15 at 18:14

score 0 · Accepted Answer · answered Mar 16 '15 at 23:06

FWIW, here's one way:

get.dtm <- function(txts) {
  require(plyr)
  dtm <- do.call(rbind.fill.matrix, lapply(txts, function(txt) t(table(scan(file = textConnection(txt), what = "character", quiet = TRUE)))))
  dtm[is.na(dtm)] <- 0
  return(dtm)
}
get.dtm(c("this is a text text", "this is just another text"))
#      a is text this another just
# [1,] 1  1    2    1       0    0
# [2,] 0  1    1    1       1    1

How to build a termdocumentmatrix in R

1 Answers1