inequality_constraint: Graphics for constraints

In mosaicCalc: R-Language Based Calculus Operations for Teaching

Graphics for constraints

Description

These functions are intended to annotate contour plots with constraint regions. Inequality constraints are shaded where the constraint is NOT satisfied. Equality constraints are shaded in a small region near where the constraint is satisfied.

Usage

inequality_constraint(
  previous = NULL,
  tilde,
  domain,
  npts = 100,
  fill = "blue",
  alpha = 1
)

equality_constraint(
  previous = NULL,
  tilde,
  domain,
  npts = 100,
  fill = "blue",
  alpha = 1
)

Arguments

previous	can be ignored by user. It supports the pipe syntax for layering graphics.
tilde	a tilde expression specifying the constraint. For an inequality constraint this should be a logical expression that is TRUE where the constraint is satisfied. For an equality constraint, the left-hand side of the tilde expression should be zero where the constraint IS satisfied.
domain	as in contour_plot(), the domain over which to graph the constraint
npts	a number specifying how finely to divide the domain in each direction. Default is 100, but this gives a discernably pixelated appearance to the shading. 200 or 300 is more appropriate for publication-quality graphics.
fill	the color to use for shading
alpha	the opacity of the shading

Value

ggplot2 graphics layers

Examples

inequality_constraint(x + y > 2 ~ y + x, domain(y=0:3, x=0:2))
equality_constraint(x + y - 2 ~ y + x, domain(y=0:3, x=0:2), npts=200, alpha=.3, fill="red")

mosaicCalc documentation built on Sept. 11, 2024, 9:10 p.m.