Why nfeature() instead of nfeat()?

[koheiw]

nfeature() and ndocument() is consistent naming, but nfeature() and ndoc() is not. Relatedly, why not topfeat() instead of topfeatures()?

[kbenoit]

We could rename the main function to nfeat(), but keep nfeature() as an invisible alias.

topfeatures() is already an exception, and I don’t think we should change it now.

[koheiw]

OK leave topfeatures() now, and add nfeat() and ndocument(). We will have

full name	alias
nfeature()	nfeat()
ndocument()	ndoc()

I can do this along with #1133.

[kbenoit]

No need to add ndocument(), but let’s add nfeat(). It’s consistent with the other function names, but also consistent with base R n* functions, e.g. nrow(), ncol(), etc