R: Plot a comparison cloud

comparison.cloud {wordcloud} | R Documentation

## Plot a comparison cloud

### 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)

    }

[Package wordcloud version 2.6 Index]