I wrote a small program to display the “Hopalong Attractor”. The calculations themselves are relatively fast, as is the scatter plot if you only use a single color.

Coloring the scatterplot as a function of the distance from the origin point, the execution time is about 6 times longer. The use of “savefig” also increases the execution time significantly.

I use jupyter-lab to run (hence pygui=false)

I think that is a common known issue of scatter plot? Or improperly programmed? Or Jupyter Lab issue?

```
using PyPlot; pygui(false) # pygui open plot in seperate interactive window if true
function hopalong(num,a,b,c) # e.g.hopalong(1e6,-1.7,0.5,1.1)
x::Float64,y::Float64 = 0,0 # origin point
u,v,d = Float64[],Float64[],Float64[] # point vectors (x,y) and distance vector(d), color c of scatter = f(d)
markerstyle="."; markersize = 0.1
for i=1:num
xx = y-sign(x)*sqrt(abs(b*x-c)); yy = a-x; x = xx; y = yy; push!(u,x); push!(v,y); push!(d,sqrt(x^2+y^2))
end
figure=PyPlot.gcf()
figure.set_size_inches(10,8)
#scatter(u,v,s=markersize,marker=markerstyle,c="black")
scatter(u,v,s=markersize,marker=markerstyle,c=d,cmap="gnuplot")
title("Orbit of Martin's Map(Hopalong attractor). Parameters: num=$num, a=$a, b=$b, c=$c,markerszie=$markersize",fontsize=10)
#savefig("Martins_Pics/hopalong@num = $num , a = $a , b = $b , c = $c.png",dpi=300)
end
hopalong(1e6,2.0,0.3,0.7)
```