entropy_kde2d {YEAB} | R Documentation |
Shannon entropy in two dimensions
Description
Shannon entropy in two dimensions
Usage
entropy_kde2d(x, y, n_grid = 150)
Arguments
x |
numeric, random vector |
y |
numeric, random vector |
n_grid |
numeric, number of grid cells to evaluate density |
Value
A numeric value of the entropy in 2D
Examples
set.seed(123)
# Generate a 2D normal distribution with a correlation of 0.6
n <- 1000
mean <- c(0, 0)
sd_x <- 1
sd_y <- 5
correlation <- 0.6
sigma <- matrix(
c(
sd_x^2,
correlation * sd_x * sd_y,
correlation * sd_x * sd_y,
sd_y^2
),
ncol = 2
)
library(MASS)
simulated_data <- mvrnorm(n, mu = mean, Sigma = sigma)
x <- simulated_data[, 1]
y <- simulated_data[, 2]
cov_matr <- cov(cbind(x, y))
sigmas <- diag(cov_matr)
det_sig <- prod(sigmas)
# According to https://en.wikipedia.org/wiki/Multivariate_normal_distribution#Differential_entropy:
normal_entropy <- function(k, pi, det_sig) {
# The left part is a constant;
(k / 2) * (1 + log(2 * pi)) + (1 / 2) * log(det_sig)
}
entropia <- normal_entropy(k = 2, pi = pi, det_sig)
print(entropia) # Should return a value close to 4.3997
result <- entropy_kde2d(x, y, n_grid = 50)
print(result) # Should return a value close to 4.2177
[Package YEAB version 1.0.6 Index]