Modify vector constraints for MatrixOfConstraints

Author: blegat

src/Utilities/matrix_of_constraints.jl

@@ -739,6 +739,32 @@ function MOI.modify(
     return
 end
 
+function MOI.modify(
+    model::MatrixOfConstraints,
+    ci::MOI.ConstraintIndex,
+    change::MOI.MultirowChange,
+)
+    r = rows(model, ci)
+    for (output_index, new_coefficient) in change.new_coefficients
+        if !modify_coefficients(
+            model.coefficients,
+            r[output_index],
+            change.variable.value,
+            new_coefficient,
+        )
+            throw(
+                MOI.ModifyConstraintNotAllowed(
+                    ci,
+                    change,
+                    "cannot set a new non-zero coefficient because no entry " *
+                    "exists in the sparse matrix of `MatrixOfConstraints`",
+                ),
+            )
+        end
+    end
+    return
+end
+
 # See https://github.com/jump-dev/MathOptInterface.jl/pull/2976
 # Ideally we would have made it so that `modify_constants` operated like
 # `modify_coefficients` and returned a `Bool` indicating success. But we didn't,

test/Utilities/test_matrix_of_constraints.jl

@@ -826,6 +826,119 @@ function test_modify_set_constants()
     return
 end
 
+function test_modify_multirow_change()
+    model = _new_VectorSets()
+    src = MOI.Utilities.Model{Int}()
+    x = MOI.add_variables(src, 2)
+    terms = [
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(2, x[1])),
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(3, x[2])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(4, x[1])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(5, x[2])),
+    ]
+    func = MOI.VectorAffineFunction(terms, [0, 0])
+    c = MOI.add_constraint(src, func, MOI.Nonnegatives(2))
+    index_map = MOI.copy_to(model, src)
+    ci = index_map[c]
+    f = MOI.get(model, MOI.ConstraintFunction(), ci)
+    @test length(f.terms) == 4
+    x1 = index_map[x[1]]
+    x2 = index_map[x[2]]
+    MOI.modify(model, ci, MOI.MultirowChange(x1, [(1, 7), (2, 8)]))
+    f = MOI.get(model, MOI.ConstraintFunction(), ci)
+    coefs = Dict(
+        (t.output_index, t.scalar_term.variable) => t.scalar_term.coefficient
+        for t in f.terms
+    )
+    @test coefs[(1, x1)] == 7
+    @test coefs[(2, x1)] == 8
+    @test coefs[(1, x2)] == 3
+    @test coefs[(2, x2)] == 5
+    return
+end
+
+function test_modify_multirow_change_single_row()
+    model = _new_VectorSets()
+    src = MOI.Utilities.Model{Int}()
+    x = MOI.add_variables(src, 2)
+    terms = [
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(2, x[1])),
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(3, x[2])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(4, x[1])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(5, x[2])),
+    ]
+    func = MOI.VectorAffineFunction(terms, [0, 0])
+    c = MOI.add_constraint(src, func, MOI.Nonnegatives(2))
+    index_map = MOI.copy_to(model, src)
+    ci = index_map[c]
+    x2 = index_map[x[2]]
+    MOI.modify(model, ci, MOI.MultirowChange(x2, [(2, 9)]))
+    f = MOI.get(model, MOI.ConstraintFunction(), ci)
+    coefs = Dict(
+        (t.output_index, t.scalar_term.variable) => t.scalar_term.coefficient
+        for t in f.terms
+    )
+    x1 = index_map[x[1]]
+    @test coefs[(1, x1)] == 2
+    @test coefs[(2, x1)] == 4
+    @test coefs[(1, x2)] == 3
+    @test coefs[(2, x2)] == 9
+    return
+end
+
+function test_modify_multirow_change_to_zero()
+    model = _new_VectorSets()
+    src = MOI.Utilities.Model{Int}()
+    x = MOI.add_variables(src, 2)
+    terms = [
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(2, x[1])),
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(3, x[2])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(4, x[1])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(5, x[2])),
+    ]
+    func = MOI.VectorAffineFunction(terms, [0, 0])
+    c = MOI.add_constraint(src, func, MOI.Nonnegatives(2))
+    index_map = MOI.copy_to(model, src)
+    ci = index_map[c]
+    x1 = index_map[x[1]]
+    MOI.modify(model, ci, MOI.MultirowChange(x1, [(1, 0)]))
+    f = MOI.get(model, MOI.ConstraintFunction(), ci)
+    coefs = Dict(
+        (t.output_index, t.scalar_term.variable) => t.scalar_term.coefficient
+        for t in f.terms
+    )
+    @test coefs[(1, x1)] == 0
+    @test coefs[(2, x1)] == 4
+    return
+end
+
+function test_modify_multirow_change_no_entry()
+    model = _new_VectorSets()
+    src = MOI.Utilities.Model{Int}()
+    x = MOI.add_variables(src, 3)
+    terms = [
+        MOI.VectorAffineTerm(1, MOI.ScalarAffineTerm(2, x[1])),
+        MOI.VectorAffineTerm(2, MOI.ScalarAffineTerm(4, x[1])),
+    ]
+    func = MOI.VectorAffineFunction(terms, [0, 0])
+    c = MOI.add_constraint(src, func, MOI.Nonnegatives(2))
+    index_map = MOI.copy_to(model, src)
+    ci = index_map[c]
+    x3 = index_map[x[3]]
+    MOI.modify(model, ci, MOI.MultirowChange(x3, [(1, 0)]))
+    change = MOI.MultirowChange(x3, [(1, 5)])
+    @test_throws(
+        MOI.ModifyConstraintNotAllowed(
+            ci,
+            change,
+            "cannot set a new non-zero coefficient because no entry " *
+            "exists in the sparse matrix of `MatrixOfConstraints`",
+        ),
+        MOI.modify(model, ci, change),
+    )
+    return
+end
+
 function test_unsupported_constraint()
     model = _new_ScalarSets()
     x = MOI.VariableIndex(1)