From 8200c003af5a5e0e370fb28128f1c15ce0eac9d3 Mon Sep 17 00:00:00 2001
From: Alinson S Xavier <axavier@anl.gov>
Date: Sun, 12 Apr 2020 11:07:09 -0500
Subject: [PATCH] Add work-in-progress JuMPSolver

---
 src/julia/src/MIPLearn.jl  |   7 +-
 src/julia/test/runtests.jl | 137 +++++++++++++++++++++++++++++++++++++
 2 files changed, 141 insertions(+), 3 deletions(-)

diff --git a/src/julia/src/MIPLearn.jl b/src/julia/src/MIPLearn.jl
index a6b9698..8603ed4 100644
--- a/src/julia/src/MIPLearn.jl
+++ b/src/julia/src/MIPLearn.jl
@@ -1,5 +1,6 @@
-module MIPLearn
-
-greet() = print("Hello World!")
+#  MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization
+#  Copyright (C) 2020, UChicago Argonne, LLC. All rights reserved.
+#  Released under the modified BSD license. See COPYING.md for more details.
 
+module MIPLearn
 end # module
diff --git a/src/julia/test/runtests.jl b/src/julia/test/runtests.jl
index e69de29..cac36ff 100644
--- a/src/julia/test/runtests.jl
+++ b/src/julia/test/runtests.jl
@@ -0,0 +1,137 @@
+#  MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization
+#  Copyright (C) 2020, UChicago Argonne, LLC. All rights reserved.
+#  Released under the modified BSD license. See COPYING.md for more details.
+
+using MIPLearn
+using Test
+using JuMP
+using Gurobi
+using PyCall
+using MathOptInterface
+const MOI = MathOptInterface
+
+miplearn = pyimport("miplearn")
+
+Instance = miplearn.Instance
+LearningSolver = miplearn.LearningSolver
+InternalSolver = miplearn.solvers.internal.InternalSolver
+
+@pydef mutable struct JuMPSolver <: InternalSolver
+    function add_constraint(self, constraint)
+    end
+
+    function clear_warm_start(self)
+    end
+
+    function fix(self, solution)
+    end
+
+    function set_gap_tolerance(self, gap_tolerance)
+    end
+
+    function set_instance(self, instance, model)
+        self.instance = instance
+        self.model = model
+    end
+
+    function set_node_limit(self)
+    end
+
+    function set_threads(self, threads)
+    end
+
+    function set_time_limit(self, time_limit)
+    end
+
+    function set_warm_start(self, solution)
+    end
+
+    function solve(self; tee=false)
+        JuMP.set_optimizer(self.model, Gurobi.Optimizer)
+        JuMP.optimize!(self.model)
+
+        primal_bound = JuMP.objective_value(self.model)
+        dual_bound = JuMP.objective_bound(self.model)
+
+        if JuMP.objective_sense(self.model) == MOI.MIN_SENSE
+            sense = "min"
+            lower_bound = dual_bound
+            upper_bound = primal_bound
+        else
+            sense = "max"
+            lower_bound = primal_bound
+            upper_bound = dual_bound
+        end
+
+        @show primal_bound, dual_bound
+
+        return Dict("Lower bound" => lower_bound,
+                    "Upper bound" => upper_bound,
+                    "Sense" => sense)
+    end
+
+    function solve_lp(self; tee=false)
+    end
+
+    function get_solution(self)
+        return Dict(JuMP.name(var) => JuMP.value(var)
+                    for var in JuMP.all_variables(self.model))
+    end
+end
+
+@pydef mutable struct KnapsackInstance <: Instance
+    function __init__(self, weights, prices, capacity)
+        self.weights = weights
+        self.prices = prices
+        self.capacity = capacity
+    end
+
+    function to_model(self)
+        model = Model()
+        n = length(self.weights)
+        @variable(model, x[1:n], Bin)
+        @objective(model, Max, sum(x[i] * self.prices[i] for i in 1:n))
+        @constraint(model, sum(x[i] * self.weights[i] for i in 1:n) <= instance.capacity)
+        return model
+    end
+
+    function get_instance_features(self)
+        return [0.]
+    end
+
+    function get_variable_features(self, var, index)
+        @show var
+        return [0.]
+    end
+end
+
+instance = KnapsackInstance([23., 26., 20., 18.],
+                            [505., 352., 458., 220.],
+                            67.0)
+model = instance.to_model()
+
+solver = JuMPSolver()
+solver.set_instance(instance, model)
+stats = solver.solve()
+# assert len(stats["Log"]) > 100
+@test stats["Lower bound"] == 1183.0
+@test stats["Upper bound"] == 1183.0
+@test stats["Sense"] == "max"
+# @test isinstance(stats["Wallclock time"], float)
+# @test isinstance(stats["Nodes"], int)
+
+solution = solver.get_solution()
+@test solution["x[1]"] == 1.0
+@test solution["x[2]"] == 0.0
+@test solution["x[3]"] == 1.0
+@test solution["x[4]"] == 1.0
+
+# stats = solver.solve_lp()
+# @test round(stats["Optimal value"], 3) == 1287.923
+#
+# solution = solver.get_solution()
+# @test round(solution["x"][0], 3) == 1.000
+# @test round(solution["x"][1], 3) == 0.923
+# @test round(solution["x"][2], 3) == 1.000
+# @test round(solution["x"][3], 3) == 0.000
+