julia> using JuMP
julia> regions = ["china", "ghana", "ee+ussr", "s-leone"]
4-element Array{String,1}:
"china"
"ghana"
"ee+ussr"
"s-leone"
julia> ports = ["accra", "freetown", "leningrad", "shanghai"]
4-element Array{String,1}:
"accra"
"freetown"
"leningrad"
"shanghai"
julia> links = [
"china" => "shanghai",
"ghana" => "accra",
"ee+ussr" => "leningrad",
"s-leone" => "freetown"
]
4-element Array{Pair{String,String},1}:
"china" => "shanghai"
"ghana" => "accra"
"ee+ussr" => "leningrad"
"s-leone" => "freetown"
julia> model = Model()
A JuMP Model
Feasibility problem with:
Variables: 0
Model mode: AUTOMATIC
CachingOptimizer state: NO_OPTIMIZER
Solver name: No optimizer attached.
julia> @variable(model, arcs[r=regions, p=ports; (r => p) in links])
JuMP.Containers.SparseAxisArray{VariableRef,2,Tuple{String,String}} with 4 entries:
[s-leone, freetown ] = arcs[s-leone,freetown]
[china, shanghai ] = arcs[china,shanghai]
[ee+ussr, leningrad] = arcs[ee+ussr,leningrad]
[ghana, accra ] = arcs[ghana,accra]
julia> arcs["s-leone", "freetown"]
arcs[s-leone,freetown]