xpress in github actions (#687)

* first test

* xpress is not available in 3.11 for macOS apparently.

.github/workflows/pythonpackage.yml

@@ -17,15 +17,18 @@ jobs:
         uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install .
       - name: install glpk
         if: matrix.os == 'ubuntu-latest'
         run: |
           sudo apt-get update -qq
           sudo apt-get install -qq glpk-utils
-      - name: Install dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install .
+      - name: install xpress
+        if: matrix.os != 'macOS-latest' || matrix.python-version < '3.11'
+        run: pip install xpress
       - name: Install gurobipy
         run: |
           python -m pip install gurobipy

doc/source/develop/add_solver.rst

@@ -154,3 +154,21 @@ Include the solver in PuLP's test suite by adding a couple of lines correspondin
     # (...)
     class MIPCL_CMDTest(BaseSolverTest.PuLPTest):
         solveInst = MIPCL_CMD
+
+
+Extra: adding a official solver API
+---------------------------------------------
+
+There are additional best practices to take into account with these solvers. The ``actualSolve`` method has the following structure::
+
+    def actualSolve(self, lp):
+        self.buildSolverModel(lp)
+        # set the initial solution
+        self.callSolver(lp)
+        # get the solution information
+        solutionStatus = self.findSolutionValues(lp)
+        return solutionStatus
+
+In addition to this, the ``buildSolverModel`` method fills a property named `lp.solverModel` in the LP problem. This property will include a pointer to the model object from the official solver API (e.g., ``gurobipy.Model`` for GUROBI).
+
+These considerations will permit a consistent, more standard way to call official solvers. In particular, they allow for detailed configuration, such as the one explained :ref:`here <solver-specific-config>`.

doc/source/guides/how_to_configure_solvers.rst

@@ -190,6 +190,7 @@ PuLP has the integrations with the official python API solvers for the following
 * Mosek (MOSEK)
 * Gurobi (GUROBI)
 * Cplex (CPLEX_PY)
+* Xpress (XPRESS_PY)
 
 These API offer a series of advantages over using the command line option:
 
@@ -218,9 +219,11 @@ Following my installation paths it would be (Linux):
 
 As you can see, it is necessary to have admin rights to install it.
 
+.. _solver-specific-config:
 Using solver-specific functionality
 **********************************************
 
+
 In order to access this functionality, the user needs to use the solver object included inside the PuLP problem. PuLP uses the ``solverModel`` attribute on the problem object. This attribute is created and filled when the method ``buildSolverModel()`` is executed.
 
 For example, using the ``CPLEX_PY`` API we can access the api object after the solving is done:

pulp/tests/test_pulp.py

@@ -1340,7 +1340,7 @@ def test_LpVariable_indexs_param(self):
             print("\t Testing 'indexs' param continues to work for LpVariable.matrix")
             # explicit param creates list of list of LpVariable
             assign_vars_matrix = LpVariable.matrix(
-                name="test", indexs=(customers, agents)
+                name="test", indices=(customers, agents)
             )
             for a in assign_vars_matrix:
                 for b in a: