Add MOI methods: delete and modify

src/MOIwrapper.jl

@@ -209,6 +209,84 @@ function MOI.add_constraint(
     return constrid
 end
 
+############################################################################################
+# Delete and modify variable
+############################################################################################
+function MOI.delete(model::Coluna.Optimizer, vi::MOI.VariableIndex)
+    MOI.modify(model, MoiObjective(), MOI.ScalarCoefficientChange(vi, 0.0))
+    for (ci, _) in model.constrs_on_single_var_to_vars
+        if ci.value == vi.value
+            MOI.delete(model, ci)
+            break
+        end
+    end
+    for (ci, _) in model.constrs
+        MOI.modify(model, ci, MOI.ScalarCoefficientChange(vi, 0.0))
+    end
+    varid = getid(model.vars[vi])
+    delete!(get_original_formulation(model.inner), varid)
+    delete!(model.moi_varids, varid)
+    delete!(model.vars, vi)
+    delete!(model.env.varids, vi)
+    return
+end
+
+function MOI.modify(
+    model::Coluna.Optimizer, ::MOI.ObjectiveFunction{MOI.ScalarAffineFunction{Float64}},
+    change::MathOptInterface.ScalarCoefficientChange{Float64}
+)
+    setperencost!(
+        get_original_formulation(model.inner), model.vars[change.variable], change.new_coefficient
+    )
+    return
+end
+
+############################################################################################
+# Delete and modify constraint
+############################################################################################
+# issue #583
+# function MOI.delete(
+#     model::Coluna.Optimizer, ci::MOI.ConstraintIndex{F,S}
+# ) where {F<:MOI.SingleVariable,S}
+#     return
+# end
+
+function MOI.delete(
+    model::Coluna.Optimizer, ci::MOI.ConstraintIndex{F,S}
+) where {F<:MOI.ScalarAffineFunction{Float64},S}
+    constrid = getid(model.constrs[ci])
+    orig_form = get_original_formulation(model.inner)
+    coefmatrix = getcoefmatrix(orig_form)
+    varids = VarId[]
+    for (varid, _) in @view coefmatrix[constrid, :]
+        push!(varids, varid)
+    end
+    for varid in varids
+        coefmatrix[constrid, varid] = 0.0
+    end
+    delete!(orig_form, constrid)
+    delete!(model.constrs, ci)
+    return
+end
+
+function MOI.modify(
+    model::Coluna.Optimizer, ci::MOI.ConstraintIndex{F,S},
+    change::MOI.ScalarConstantChange{Float64}
+) where {F<:MOI.ScalarAffineFunction{Float64},S}
+    setperenrhs!(get_original_formulation(model.inner), model.constrs[ci], change.new_constant)
+    return
+end
+
+function MOI.modify(
+    model::Coluna.Optimizer, ci::MOI.ConstraintIndex{F,S},
+    change::MOI.ScalarCoefficientChange{Float64}
+) where {F<:MOI.ScalarAffineFunction{Float64},S}
+    varid = getid(model.vars[change.variable])
+    constrid = getid(model.constrs[ci])
+    getcoefmatrix(get_original_formulation(model.inner))[constrid, varid] = change.new_coefficient
+    return
+end
+
 ############################################################################################
 # Get variables
 ############################################################################################

src/MathProg/MathProg.jl

@@ -8,7 +8,7 @@ import TimerOutputs
 import ..Coluna # for NestedEnum (types.jl:210)
 using ..ColunaBase
 
-import Base: haskey, length, iterate, diff
+import Base: haskey, length, iterate, diff, delete!
 
 using DynamicSparseArrays, Logging, Printf
 

src/MathProg/varconstr.jl

@@ -453,6 +453,26 @@ function deactivate!(form::Formulation, f::Function)
     return
 end
 
+## delete
+"""
+    delete!(formulation, varconstrid)
+    delete!(formulation, varconstr)
+
+Delete a variable or a constraint from a formulation.
+"""
+function Base.delete!(form::Formulation, varid::VarId)
+    delete!(form.manager.vars, varid)
+    delete!(form.buffer.var_buffer.added, varid)
+    return
+end
+Base.delete!(form::Formulation, var::Variable) = delete!(form, getid(var))
+
+function Base.delete!(form::Formulation, constrid::ConstrId)
+    delete!(form.buffer.constr_buffer.added, constrid)
+    delete!(form.manager.constrs, constrid)
+end
+Base.delete!(form::Formulation, constr::Constraint) = delete!(form, getid(constr))
+
 ## explicit
 """
     isexplicit(formulation, varconstr)

test/MathOptInterface/MOI_wrapper.jl

@@ -113,9 +113,7 @@ end
 
 const UNSUPPORTED_TESTS = [
     "solve_qcp_edge_cases", # Quadratic constraints not supported
-    "delete_nonnegative_variables", # variable deletion not supported
-    "delete_variable", # variable deletion not supported
-    "delete_variables", # variable deletion not supported
+    "delete_nonnegative_variables", # `VectorOfVariables`-in-`Nonnegatives` not supported 
     "variablenames", # Coluna retrieves the name of the variable
     "delete_soc_variables", # soc variables not supported
     "solve_qp_edge_cases", # Quadratic objective not supported
@@ -192,12 +190,10 @@ const CONSTRAINTDUAL_SINGLEVAR = [
     "linear14"
 ]
 
-const MODIFY_DELETE = [
-    # BUG
-    "linear1", # modify
-    "linear5", # modify
-    "linear11", # delete
-    "linear14" # delete
+const DELETE_SINGLEVAR_CONSTR = [
+    # BUG: issue #583
+    "linear5",
+    "linear14"
 ]
 
 const UNCOVERED_TERMINATION_STATUS = [
@@ -240,7 +236,7 @@ end
 
 @testset "Continuous Linear" begin
     MOIT.contlineartest(BRIDGED, CONFIG, vcat(
-        CONSTRAINTDUAL_SINGLEVAR, MODIFY_DELETE, UNCOVERED_TERMINATION_STATUS, SET_CONSTRAINTSET, [
+        CONSTRAINTDUAL_SINGLEVAR, DELETE_SINGLEVAR_CONSTR, UNCOVERED_TERMINATION_STATUS, SET_CONSTRAINTSET, [
             "partial_start" # VariablePrimalStart not supported
         ]
     ))