ldboundary: Linear Discriminant Boundary

In phonTools: Tools for Phonetic and Acoustic Analyses

Linear Discriminant Boundary

Description

Given two mean vectors and a covariance matrix (and optional prior probabilities), this function will return the slope and intercept of the boundary line between the two categories.

Usage

ldboundary (mean1, mean2, covariance, prior1 = .5, prior2 = .5, add = F, ...)

Arguments

mean1	A mean vector for category 1, must contain 2 elements.
mean2	A mean vector for category 2, must contain 2 elements.
covariance	A 2x2 covariance matrix for both distributions.
prior1	The prior probability of category 1.
prior2	The prior probability of category 2.
add	If TRUE, the boundary line is added top the plot.
...	Additional parameters are passed to the internal call of the line plotting function, in the event that add = T.

Value

The slope and intercept of the boundary line are returned.

Author(s)

Santiago Barreda <[e-mail]>

References

http://en.wikipedia.org/wiki/Linear_discriminant_analysis https://onlinecourses.science.psu.edu/stat557/book/export/html/35

Examples

## create two groups with the same covariance patterns
#group1 = rmvtnorm (200, means= c(0,0), k=2, sigma = -.4)
#group2 = rmvtnorm (200, means= c(3,3), k=2, sigma = -.4)
#covariance = (var (group1) + var (group2)) / 2

## plot groups and boundary line between categories.
#plot (group1, col = 2, pch = 16, ylim = c(-2,5), xlim = c(-2,5))
#points (group2, col = 4, pch = 16)
#ldboundary (c(0,0), c(3,3), covariance, add = TRUE)

phonTools documentation built on Nov. 21, 2023, 1:07 a.m.