Added the simple mip interface (untested)

requirements.txt

@@ -4,7 +4,7 @@ networkx>=2.1
 pandas>=1.1
 xlwt>=1.3.0
 xlrd>=1.1.0
-ortools>=9.8.0
+# ortools>=9.8.0
 matplotlib>=2.1.1
 qtconsole>=4.3.1
 pyDOE>=0.3.8
@@ -28,4 +28,5 @@ windpowerlib
 pvlib
 hyperopt
 requests
-pytest >= 7.2.0
+pytest >= 7.2.0
+highspy >= 1.5.3

src/GridCalEngine/Core/Compilers/circuit_to_bentayga.py

@@ -51,6 +51,7 @@
         BENTAYGA_AVAILABLE = True
 
 except ImportError:
+    btg = None
     BENTAYGA_AVAILABLE = False
 
 # numpy integer type for bentayga's uword

src/GridCalEngine/Core/Compilers/circuit_to_newton_pa.py

@@ -77,6 +77,7 @@
                           f"instead of {NEWTON_PA_VERSION}")
 
 except ImportError as e:
+    npa = None
     NEWTON_PA_AVAILABLE = False
     NEWTON_PA_VERSION = ''
 

src/GridCalEngine/Core/Compilers/circuit_to_optimods.py

@@ -21,7 +21,8 @@
 import json
 import pandas as pd
 from GridCalEngine.Core.Devices.multi_circuit import MultiCircuit
-from GridCalEngine.basic_structures import Logger, SolverType
+from GridCalEngine.enumerations import SolverType
+from GridCalEngine.basic_structures import Logger
 from GridCalEngine.Simulations.PowerFlow.power_flow_options import PowerFlowOptions
 from GridCalEngine.Simulations.PowerFlow.power_flow_results import PowerFlowResults
 from GridCalEngine.Simulations.PowerFlow.power_flow_ts_results import PowerFlowTimeSeriesResults

src/GridCalEngine/Core/Compilers/circuit_to_pgm.py

@@ -43,6 +43,7 @@
 
     PGM_AVAILABLE = True
 except ImportError:
+    pgm = None
     PGM_AVAILABLE = False
 
 '''

src/GridCalEngine/Utils/MIP/SimpleMip/__init__.py

@@ -0,0 +1,20 @@
+# GridCal
+# Copyright (C) 2015 - 2023 Santiago Peñate Vera
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 3 of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+from GridCalEngine.Utils.MIP.SimpleMip.lpexp import LpExp
+from GridCalEngine.Utils.MIP.SimpleMip.lpvar import LpVar
+from GridCalEngine.Utils.MIP.SimpleMip.problem import LpModel, get_available_mip_solvers, set_var_bounds

src/GridCalEngine/Utils/MIP/SimpleMip/highs.py

@@ -0,0 +1,88 @@
+# GridCal
+# Copyright (C) 2015 - 2023 Santiago Peñate Vera
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 3 of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+from __future__ import annotations
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:  # Only imports the below statements during type checking
+    from GridCalEngine.Utils.MIP.SimpleMip.problem import Problem
+
+try:
+    import highspy
+    HIGHS_AVAILABLE = True
+except ImportError:
+    highspy = None
+    HIGHS_AVAILABLE = False
+
+
+def solve_with_highs(mip: Problem, verbose: int = 0):
+    """
+    Solve MIP using Highs via its python interface
+    :param mip: Problem to be solved (results are inserted in-place)
+    :param verbose: print info? for values > 0
+    """
+    if highspy is None:
+        raise Exception("No highspy available, try installing with: pip install highspy")
+
+    # declare the solver
+    h = highspy.highs.Highs()
+
+    # declare the LP problem
+    lp = highspy.highs.HighsLp()
+
+    # set the sense
+    lp.sense_ = highspy.highs.ObjSense.kMinimize if mip.is_minimize() else highspy.highs.ObjSense.kMaximize
+
+    # set the var information
+    lp.col_lower_, lp.col_cost_, lp.col_upper_, is_int_list = mip.get_var_data()
+    lp.offset_ = mip.objective.offset
+
+    for i in is_int_list:
+        lp.integrality_.append(i)
+
+    # set the constraints information
+    lp.row_lower_, A, lp.row_upper_ = mip.get_coefficients_data()
+    lp.num_col_ = A.shape[1]
+    lp.num_row_ = A.shape[0]
+
+    lp.a_matrix_.start_ = A.indptr
+    lp.a_matrix_.index_ = A.indices
+    lp.a_matrix_.value_ = A.data
+
+    # send the model to the solver
+    h.passModel(lp)
+
+    # solve
+    h.run()
+
+    # gather results
+    solution = h.getSolution()
+    basis = h.getBasis()
+    info = h.getInfo()
+    model_status = h.getModelStatus()
+
+    if verbose > 0:
+        print("Model status = ", h.modelStatusToString(model_status))
+        print("Optimal objective = ", info.objective_function_value)
+        print("Iteration count = ", info.simplex_iteration_count)
+        print("Primal solution status = ", h.solutionStatusToString(info.primal_solution_status) )
+
+    mip.set_solution(col_values=solution.col_value,
+                     col_duals=solution.col_dual,
+                     row_values=solution.row_value,
+                     row_duals=solution.row_dual,
+                     fixed_values=info.objective_function_value,
+                     optimal_values=model_status == highspy.highs.HighsModelStatus.kOptimal)

src/GridCalEngine/Utils/MIP/SimpleMip/lpcst.py

@@ -0,0 +1,101 @@
+# GridCal
+# Copyright (C) 2015 - 2023 Santiago Peñate Vera
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 3 of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+from __future__ import annotations
+from typing import Tuple, TYPE_CHECKING
+
+if TYPE_CHECKING:  # Only imports the below statements during type checking
+    from GridCalEngine.Utils.MIP.SimpleMip.lpexp import LpExp
+    from GridCalEngine.Utils.MIP.SimpleMip.lpvar import LpVar
+
+
+class LpCst:
+    """
+    Constraint
+    """
+    def __init__(self, linear_expression: LpExp, sense: str, coefficient: float,
+                 name="", internal_index: int = 0):
+        """
+        constraint (<=, ==, >=) rhs
+
+        :param linear_expression:
+        :param sense: <=, ==, >=
+        :param coefficient:
+        :param name:
+        :param internal_index:
+        """
+        assert sense in ["<=", "==", ">="]
+
+        self.name = name
+        self.linear_expression = linear_expression
+        self.sense = sense
+        self.coefficient = coefficient  # Right-hand side value
+        self._index: int = internal_index  # internal index to the solver
+
+    def copy(self) -> "LpCst":
+        """
+        Make a deep copy of this constraint
+        :return: Constraint
+        """
+        return LpCst(linear_expression=self.linear_expression.copy(),
+                     sense=self.sense,
+                     coefficient=self.coefficient,
+                     name=self.name,
+                     internal_index=self._index)
+
+    def get_bounds(self) -> Tuple[float, float]:
+        """
+        Get the constraint bounds
+        :return: lhs <= constraint <= rhs
+        """
+        MIP_INF = 1e20
+        if self.sense == '==':
+            return self.coefficient, self.coefficient
+        elif self.sense == '<=':
+            return -MIP_INF, self.coefficient
+        elif self.sense == '>=':
+            return self.coefficient, MIP_INF
+        else:
+            raise Exception(f"Invalid sense: {self.sense}")
+
+    def set_index(self, index: int) -> None:
+        """
+        Set the internal indexing
+        :param index: constraint index in the solver
+        """
+        self._index = index
+
+    def get_index(self) -> int:
+        """
+        Get internal index
+        :return: int
+        """
+        return self._index
+
+    def add_term(self, var: LpVar, coeff: float):
+        """
+        Add a term to the constraint
+        :param var: Variable
+        :param coeff: coefficient
+        """
+        self.linear_expression += coeff * var
+
+    def add_var(self, var: LpVar):
+        """
+        Add a term to the constraint
+        :param var: Variable
+        """
+        self.linear_expression += var