gp.jl

#=
Objective:      Find minimum time vehicle control program
Terminal Set:   x (position)
                v (velocity)
                -1
Function Set:   +, -, *, DIV, GT, ABS
Cost:           Time to bring behicle to phase plane origin
                averaged over 20 random initial conditions
Gen. Limit:     50
Pop. Size:      500
Max Initial Tree Depth: 6
Init. Method:   Ramped half-and-half
Max. Tree depth: 17
X-Over Prob.:   0.9
Mutation prob.: 0
Number of elites: 2
Selection:      Tournament
=#

function GT(a,b)
    if a > b
        return 1
    else
        return -1
    end
end

function DIV(a,b)
    if abs(b) < 10.0^-10
        return 1
    else
        return a/b
    end
end

function create_single_full_tree(depth, fs, ts)
    # If we are not at the bottom
    if depth == 1
        return Expr(:call, fs[rand(1:length(fs))], ts[rand(1:length(ts))], ts[rand(1:length(ts))])
    else
        return Expr(:call, fs[rand(1:length(fs))], create_single_full_tree(depth-1, fs, ts), create_single_full_tree(depth-1, fs, ts))
    end
end

function main()
    fs = [:+, :-, :DIV, :GT]
    ts = [:x, :v, -1]
    tst = create_single_full_tree(4, fs, ts)
end
main()