Cosine similarity of 2 DTMs in R

Question

I have 2 Document term matrices:

1. DTM 1 has say 1000 vectors(1000 docs) and
2. DTM2 has 20 vectors (20 docs)

So basically I want to compa

Answer 1

Here is a way to calculate the cosine distance between two matrices. The use of tm is just for data purposes...

library(slam)
library(tm)
data("acq")
data("crude")

dtm <- DocumentTermMatrix(c(acq, crude))

index <- sample(1:70, size = 10)

dtm1 <- dtm[index, ]
dtm2 <- dtm[-index, ]

cosine_sim <- tcrossprod_simple_triplet_matrix(dtm1, dtm2)/sqrt(row_sums(dtm1^2) %*% t(row_sums(dtm2^2)))

The cosine function was adapted from this SO post: R: Calculate cosine distance from a term-document matrix with tm and proxy