Beta.gfx.poly.qdf: Coordinate Generation for Marking an Area Under the Curve for...

In betafunctions: Functions for Working with Two- And Four-Parameter Beta Probability Distributions and Psychometric Analysis of Classifications

Coordinate Generation for Marking an Area Under the Curve for the Beta Quantile Density Distribution.

Description

Plotting tool, producing a two-column matrix with values of y corresponding to locations on x. Useful for shading areas under the curve when tracing the line for the Beta probability quantile functions.

Usage

Beta.gfx.poly.qdf(from, to, by, alpha, beta, l = 0, u = 1)

Arguments

from	The point of the x-axis from where to start producing y-quantile values.
to	The point of the x-axis to where y-quantile values are to be produced.
by	The resolution (or spacing) at which to produce y-density values.
alpha	The alpha shape-parameter value for the Standard Beta probability distribution.
beta	The beta shape-parameter for the Standard Beta probability distribution.
l	The lower-bound location parameter of the Beta distribution.
u	The upper-bound location parameter of the Beta distribution.

Value

A two-column matrix with quantile-values of y to plot against corresponding location values of x.

Examples

# To box in an area under a four-parameter Beta quantile distribution with
# location parameters l = .25 and u = 75, and shape parameters alpha = 5 and
# beta = 3, from .4 to .6:
plot(NULL, xlim = c(0, 1), ylim = c(0, 1))
coords <- Beta.gfx.poly.qdf(from = 0.4, to = 0.6, by = 0.001, alpha = 5,
beta = 3, l = 0.25, u = 0.75)
polygon(coords)

betafunctions documentation built on May 29, 2024, 1:13 a.m.