addGGContour: Add Contour Lines to Gradient Field Heatmap.

In kerschke/mogsa: A Multi-Objective Optimization Algorithm Based on Multi-Objective Gradients

Description

Add contour lines of the separate objectives to the heatmap of the cumulated path lengths.

Usage

addGGContour(g, lower, upper, fn1, fn2, fn3, log.scale = TRUE,
  col1 = "goldenrod1", col2 = "white", col3 = "cyan3",
  n.points = 30L, ...)

Arguments

g	[ggplot] ggplot-object as created by ggplotHeatmap.
lower	[numeric(d)] Vector of lower bounds.
upper	[numeric(d)] Vector of upper bounds.
fn1	[function] The first objective used for computing the multi-objective gradient.
fn2	[function] The second objective used for computing the multi-objective gradient.
fn3	[function] The third objective (if existing) used for computing the multi-objective gradient.
log.scale	[logical(1L)] Should the resulting heights be displayed on a log-scale? The default is TRUE.
col1	[character(1L)] Color used for the contour lines of the first objective (default: "goldenrod1").
col2	[character(1L)] Color used for the contour lines of the second objective (default: "white").
col3	[character(1L)] Color used for the contour lines of the third objective (default: "cyan3").
n.points	[integer(1L)] Number of points used for computing the contour lines. The default is 30L.
...	[any] Further arguments to be passed to the geom_tile function of ggplot.

Value

[ggplot]
A ggplot object displaying the multi-objective gradient landscape.

Examples

# Define two single-objective test problems and a grid of points:
fn1 = function(x) sum((x - c(0.2, 1))^2)
fn2 = function(x) sum((x - c(0.5, 0.5))^2)
points = as.matrix(expand.grid(x1 = seq(0, 0.7, 0.005), x2 = seq(0, 1.25, 0.005)))

# Compute the corresponding gradients and the cumulated path lengths:
gradients = computeGradientField(points, fn1, fn2)
x = computeCumulatedPathLengths(points, gradients)

# Visualize the resulting multi-objective "landscape":
g = ggplotHeatmap(x)
g

# Add dashed contour lines to the plot:
addGGContour(g = g, lower = c(0, 0), upper = c(0.7, 1.25),
  fn1 = fn1, fn2 = fn2, linetype = "dashed")

kerschke/mogsa documentation built on July 11, 2019, 11:52 p.m.