Smoothing become zero when all the associated documents are empty

[koheiw]

When colSums(z) = s is all zero, then the mean frequency mean(s) = a = 0. a <- max(mean(s), 1 / length(s)) will avoid this.

wordmap/R/textmodel.R

Lines 150 to 170 in d832702

	} else {
	weight <- matrix(rep(1, ncol(w) * ncol(y)), ncol = ncol(w), nrow = ncol(y),
	dimnames = list(colnames(y), colnames(w)))
	}
	m <- colSums(w)
	for (key in sort(featnames(y))) {
	if (verbose) cat(sprintf(' label = "%s"\n', key))
	z <- w[as.logical(y[,key] > 0),]
	s <- colSums(z)
	if (old) {
	v0 <- m - s + smooth
	v1 <- s + smooth
	} else {
	if (smooth >= 1.0)
	warning("The value of smooth became fractional in wordmap v0.92")
	a <- mean(s)
	v0 <- m - s + (a * smooth)
	v1 <- s + (a * smooth)
	}
	model[key,] <- log(v1 / sum(v1)) - log(v0 / sum(v0)) # log-likelihood ratio