R: Utilities for count matrices

counts {maptpx} | R Documentation

## Utilities for count matrices

### Description

Tools for manipulating (sparse) count matrices.

### Usage

    normalize(x,byrow=TRUE)
    stm_tfidf(x)

### Arguments

`x` | A `simple_triplet_matrix` or `matrix` of counts.
`byrow` | Whether to normalize by row or column totals.

### Value

`normalize` divides the counts by row or column totals, and `stm_tfidf` returns a matrix with entries x_{ij} \log[ n/(d_j+1) ], where x_{ij} is term-j frequency in document-i, and d_j is the number of documents containing term-j.

### Author(s)

Matt Taddy mataddy@gmail.com

### Examples

    normalize( matrix(1:9, ncol=3) )
    normalize( matrix(1:9, ncol=3), byrow=FALSE )

    (x <- matrix(rbinom(15,size=2,prob=.25),ncol=3))
    stm_tfidf(x)

[Package maptpx version 1.9-7 Index]