R: Cosine Measure (Matrices)

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 f.wild@open.ac.uk

### References

Leydesdorff, L. (2005) Similarity Measures, Author Cocitation Analysis,and Information Theory. In: JASIST 56(7), pp.769-772.

### See Also

`cor`

### 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)

[Package lsa version 0.73.1 Index]