| cosine {lsa} | R Documentation |
Cosine Measure (Matrices)
Description
Calculates the cosine measure between two vectors or between all column vectors of a matrix.
Usage
cosine(x, y = NULL)
Arguments
x | A vector or a matrix (e.g., a document-term matrix). |
y | Optional: a vector with compatible dimensions to x. If `NULL', all column vectors of x are correlated. |
Details
cosine() calculates a similarity matrix between all column vectors of a matrix x. This matrix might be a document-term matrix, so columns would be expected to be documents and rows to be terms.
When executed on two vectors x and y, cosine() calculates the cosine similarity between them.
Value
Returns a n*n similarity matrix of cosine values, comparing all n column vectors against each other. Executed on two vectors, their cosine similarity value is returned.
Note
The cosine measure is nearly identical with the pearson correlation coefficient (besides a constant factor)cor(method="pearson"). For an investigation on the differences in the context of textmining see (Leydesdorff, 2005).
Author(s)
Fridolin Wild fridolin.wild@wu-wien.ac.at
References
Leydesdorff, L. (2005) Similarity Measures, Author Cocitation Analysis,and Information Theory. In: JASIST 56(7), pp.769-772.
See Also
Examples
## the cosinus measure between two vectors vec1 = c( 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0 ) vec2 = c( 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0 ) cosine(vec1,vec2) ## the cosine measure for all document vectors of a matrix vec3 = c( 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0 ) matrix = cbind(vec1,vec2, vec3) cosine(matrix)