a matrix with W rows, one for each term in the vocabulary, and K
columns, one for each topic, where each column sums to one. Each column is the
multinomial distribution over terms for a given topic in an LDA topic model.
term.frequency
an integer vector of length W containing the frequency
of each term in the vocabulary.
vocab
a character vector of length W containing the unique terms in
the corpus.
topic.proportion
a numeric vector of length K containing the proportion
of each topic in the corpus.