comparison.cloud: Plot a comparison cloud

In wordcloud: Word Clouds

Description

Plot a cloud comparing the frequencies of words across documents.

Usage

comparison.cloud(term.matrix,scale=c(4,.5), max.words=300,
	random.order=FALSE, rot.per=.1,
	colors=brewer.pal(max(3,ncol(term.matrix)),"Dark2"),
	use.r.layout=FALSE, title.size=3,
	title.colors=NULL, match.colors=FALSE,
	title.bg.colors="grey90", ...)

Arguments

term.matrix	A term frequency matrix whose rows represent words and whose columns represent documents.
scale	A vector of length 2 indicating the range of the size of the words.
max.words	Maximum number of words to be plotted. least frequent terms dropped
random.order	plot words in random order. If false, they will be plotted in decreasing frequency
rot.per	proportion words with 90 degree rotation
colors	Color words in the order of columns in term.matrix
use.r.layout	if false, then c++ code is used for collision detection, otherwise R is used
title.size	Size of document titles
title.colors	Colors used for document titles. See details.
match.colors	Logical: should colors document titles colors match word colors? See details.
title.bg.colors	Colors used for the background of document titles.
...	Additional parameters to be passed to text (and strheight,strwidth).

Details

Let p_{i,j} be the rate at which word i occurs in document j, and p_j be the average across documents(∑_ip_{i,j}/ndocs). The size of each word is mapped to its maximum deviation ( max_i(p_{i,j}-p_j) ), and its angular position is determined by the document where that maximum occurs.

If title.colors is not NULL, it is used for document titles and match.colors is ignored.

Value

nothing

Examples

if(require(tm)){
	data(SOTU)
	corp <- SOTU
	corp <- tm_map(corp, removePunctuation)
	corp <- tm_map(corp, content_transformer(tolower))
	corp <- tm_map(corp, removeNumbers)
	corp <- tm_map(corp, function(x)removeWords(x,stopwords()))

	term.matrix <- TermDocumentMatrix(corp)
	term.matrix <- as.matrix(term.matrix)
	colnames(term.matrix) <- c("SOTU 2010","SOTU 2011")
	comparison.cloud(term.matrix,max.words=40,random.order=FALSE)
	comparison.cloud(term.matrix,max.words=40,random.order=FALSE,
		title.colors=c("red","blue"),title.bg.colors=c("grey40","grey70"))
	comparison.cloud(term.matrix,max.words=40,random.order=FALSE,
		match.colors=TRUE)

}

wordcloud documentation built on May 1, 2019, 8:47 p.m.