entropy {partitionComparison}

Entropy

Description

Compute the Shannon entropy

-\sum_{i} p_i \log_b p_i

Usage

entropy(x, log_base)

## S4 method for signature 'numeric,numeric'
entropy(x, log_base)

## S4 method for signature 'Partition,numeric'
entropy(x, log_base)

## S4 method for signature 'ANY,missing'
entropy(x, log_base = exp(1))

Arguments

x

A probability distribution

log_base

Optional base of the logarithm (default: e)

Methods (by class)

• entropy(x = Partition, log_base = numeric): Entropy of a partition represented by x

Hint

This method is used internally for measures based on information theory

Author(s)

Fabian Ball [e-mail]

Examples

isTRUE(all.equal(entropy(c(.5, .5)), log(2)))
isTRUE(all.equal(entropy(c(.5, .5), 2), 1))
isTRUE(all.equal(entropy(c(.5, .5), 4), .5))

# Entropy of a partition
isTRUE(all.equal(entropy(new("Partition", c(0, 0, 1, 1, 1))), entropy(c(2/5, 3/5))))