x <- presidential_debates_2012[["dialogue"]]
plot(ngram_collocations(x))
## Warning in melt.data.table(x, id = c("Grams"), variable.name = "Method", :
## 'measure.vars' [length.x, frequency, G2, length.y, ...] are not all of the
## same type. By order of hierarchy, the molten data value column will be of
## type 'double'. All measure variables not of type 'double' will be coerced
## to. Check DETAILS in ?melt.data.table for more on coercion.
lengths appear to not get merged properly.