How can I plot mixed integer problem result?

Question

I solved a linear bi-objective mixed integer problem and I want to plot the results. results include lines and points. for example

list=[([0.0; 583000.0], 0), ([190670.0; 149600.0], 0), ([69686.0, 385000.0], 1), ([33296.0, 484000.0], 1), ([136554.0, 2.38075e5], 1), ([24556.0, 503800.0], 0), ([47462.0, 437800.0], 1), ([129686.0, 253000.0], 1), ([164278.0, 178200.0], 1)]

In this list third point ([69686.0, 385000.0], 1) second element 1 is determined that this point connected by a line to prior point ([190670.0; 149600.0], 0) is connected to second point by a line.

I coded that as follow:

using  JuMP,Plots

list=[([0.0, 583000.0], 0), ([24556.0, 503800.0], 0), ([33296.0, 484000.0],1), ([47462.0, 437800.0], 1), ([69686.0, 385000.0], 1), ([129686.0, 253000.0], 1), ([136554.0, 23805.0], 1), ([164278.0, 178200.0], 1), ([190670.0, 149600.0], 0)]

x=zeros(1,1)
for i=1:size(list,1)
    x=[x;list[i][1][1]]
end
row=1
x = x[setdiff(1:end, row), :]

y=zeros(1,1)
for i=1:size(list,1)
    y=[y;list[i][1][2]]
end
row=1
y = y[setdiff(1:end, row), :]

for i=2:size(list,1)
    if list[i][2]==0
        plot(Int(x[i]),Int(y[i]),seriestype=:scatter)
        plot(Int(x[i+1]),Int(y[i+1]),seriestype=:scatter)
    end
    if list[i][2]==1
        plot(Int(x[i]),Int(y[i]))
        plot(Int(x[i+1]),Int(y[i+1]))
    end
end

but it is not worked. would you please help me. thanks

Answer 1

You can simply push each line segment's x and y values to two separate arrays, x and y in the code below. After each line segment's values (i.e. x1 and x2 or y1 and y2) put a NaN into the arrays. This will prevent connecting a line segment to the next one if there should not be a connection. (for example, the case you see 1 and then a 0). And finally plot(x, y).

The following code snippet does it. Note that allx and ally are used to hold all points regardless of connection status. You may want to exclude connected points from them. x and y holds connected line segments.

using Plots
x, y, allx, ally = Float64[], Float64[], Float64[], Float64[]

# iterate through list
for i = 1:length(list)-1
    if list[i+1][2] == 1
        # push x1 from the first point, x2 from the second and a `NaN`
        push!(x, list[i][1][1], list[i+1][1][1], NaN)
        # push y1, y2, `NaN`
        push!(y, list[i][1][2], list[i+1][1][2], NaN)
    end
    push!(allx, list[i][1][1])
    push!(ally, list[i][1][2])
end
push!(allx, list[end][1][1])
push!(ally, list[end][1][2])
# scatter all points
scatter(allx, ally)
# plot connections with markers
plot!(x, y, linewidth=2, color=:red, marker=:circle)

This should hopefully give you the plot you wanted.

---

If you happen to use Gadfly.jl instead of Plots.jl, you can get a similar plot with

using Gadfly
connectedpoints = layer(x=x, y=y, Geom.path, Geom.point, Theme(default_color="red"))
allpoints = layer(x=allx, y=ally, Geom.point)

plot(connectedpoints, allpoints)

---

As a side note if you plan to plot another series on top of a plot object already created, you should use plot! instead of plot.