📂Julia

Methods for Coloring Up to a Certain Value from Curves in Julia / Between Two Curves / Inside a Closed Curve

Fill up to a Specific Value¹

Using attributes fillrange=a, fillalpha=b, fillcolor=:color in plot(), it colors with :color to the value a from the plotted curve with the transparency b. It works the same by writing fill=(a,b,:color). That is, the following two codes are the same.

plot(x,y, fillrange=a, fillalpha=b, fillcolor=:color)
plot(x,y, fill=(a,b,:color))

It seems to be a bug, but selecting the value of fillrange as $(0,1)$ does not get colored.

using Plots

random_walk = cumsum(rand(20).-.5)

p1 = plot(random_walk,fill=(1,0.2,:lime), lw=3, legend=:bottomright)
p2 = plot(random_walk,fill=(2,0.2,:tomato), lw=3, legend=:bottomright)
plot(p1, p2)

Filling Between Two Curves

By putting one of the curve’s function values into fillalpha, the area between two curves gets colored.

rw = random_walk

plot([rw rw.+1],fill=(rw.+1,0.2,:lime), lw=3, legend=:bottomright)

Filling Inside a Closed Curve

The inside gets colored if fillalpha’s value is chosen not only from $(0,1)$.

theta = range(0,2pi, length=40)
x = cos.(theta)
y = sin.(theta)

plot(x, y, fill=(1,0.2,:lime), xlim=(-3,3), ylim=(-1.5,1.5), size=(800,400), lw=3)

Environment

• OS: Windows10
• Version: Julia 1.6.2, Plots 1.23.6