Read in a term document matrix in the .ldac sparse matrix format popularized by David Blei's C code implementation of lda.
readLdac(filename)An input file or filepath to be processed
A documents object in our format
ldac expects a file name or path that contains a file in Blei's LDA-C
format. From his ReadMe: "The data is a file where each line is of the form:
[M] [term_1]:[count] [term_2]:[count] ... [term_N]:[count]
where [M] is the number of unique terms in the document, and the [count] associated with each term is how many times that term appeared in the document. Note that [term_1] is an integer which indexes the term; it is not a string."
Because R indexes from one, the values of the term indices are incremented by one on import.