maptpx (version 1.9-2)

counts: 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.

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)