Option to change the case of the text. Value should be "upper",
"lower", or NULL (no change).
remove.punct
Logical; should punctuation be removed?
remove.numbers
Logical; should numbers be removed?
fix.spacing
Logical; should multi/trailing spaces be collapsed/removed.
Details
The input text x must already be in the correct form for
ngram(), i.e., a single string (character vector of length 1).
The case argument can take 3 possible values: NULL, in which
case nothing is done, or lower or upper, wherein the case of
the input text will be made lower/upper case, repesctively.