comparison.cloud
Plot a comparison cloud
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(\(\sum_ip_{i,j}/ndocs\)). 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
# NOT RUN {
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)
}
# }