Bugfix and testing for unconstrained optimization (#162)

pyoptsparse/pyCONMIN/pyCONMIN.py

@@ -121,7 +121,7 @@ def __call__(
             # least one constraint. So we will add one
             # automatically here:
             self.unconstrained = True
-            optProb.dummyConstraint = False
+            optProb.dummyConstraint = True
 
         # Save the optimization problem and finalize constraint
         # Jacobian, in general can only do on root proc
@@ -189,7 +189,12 @@ def cnmngrad(n1, n2, x, f, g, ct, df, a, ic, nac):
             nn3 = max(nn2, ndv)
             nn4 = max(nn2, ndv)
             nn5 = 2 * nn4
-            gg = np.zeros(ncn, np.float)
+
+            if ncn > 0:
+                gg = np.zeros(ncn, np.float)
+            else:
+                gg = np.array([0], np.float)
+
             if self.getOption("IPRINT") >= 0 and self.getOption("IPRINT") <= 4:
                 iprint = self.getOption("IPRINT")
             else:

pyoptsparse/pyNLPQLP/pyNLPQLP.py

@@ -148,7 +148,7 @@ def __call__(
 
         if len(optProb.constraints) == 0:
             self.unconstrained = True
-            optProb.dummyConstraint = False
+            optProb.dummyConstraint = True
 
         # Save the optimization problem and finalize constraint
         # Jacobian, in general can only do on root proc

pyoptsparse/pyPSQP/pyPSQP.py

@@ -158,10 +158,13 @@ def __call__(
         # Set the number of nonlinear constraints snopt *thinks* we have:
         if self.unconstrained:
             ncon = 0
-            cf = [0.0]
-            cl = []
-            cu = []
-            ic = []
+            cf = np.zeros(1)
+            cl = np.zeros(1)
+            cu = np.zeros(1)
+            ic = np.zeros(1)
+            # as done for SLSQP, we need this dummy constraint to make the code work
+            optProb.dummyConstraint = True
+
         else:
             indices, blc, buc, fact = self.optProb.getOrdering(["ne", "le", "ni", "li"], oneSided=oneSided)
             ncon = len(indices)

test/test_rosenbrock.py

@@ -0,0 +1,243 @@
+"""Test solution of Rosenbrock problem"""
+
+import unittest
+import numpy as np
+from numpy.testing import assert_allclose
+from pyoptsparse import Optimization, OPT, History
+from pyoptsparse.pyOpt_error import Error
+
+
+class TestRosenbrock(unittest.TestCase):
+
+    ## Solve unconstrained Rosenbrock problem.
+    #  This problem is scalable w.r.t. design variables number.
+    #  We select a problem with 4 design variables, but the
+    #  location and value of the minimum do not change with DV
+    #  dimensionality
+    #
+    #
+    #  min   100 * (x[i + 1] - x[i] ** 2) ** 2 + (1 - x[i]) ** 2
+    #
+    #  The minimum is located at x=(1,....,1) where x
+    #  is an arbitrarily sized vector depending on the number N
+    #  of design variables.
+    #  At the optimum, the function is f(x) = 0.
+    #  We select a random initial point for our test.
+    ##
+
+    def objfunc(self, xdict):
+        self.nf += 1
+        x = xdict["xvars"]
+
+        funcs = {}
+        funcs["obj"] = 0
+
+        for i in range(len(x) - 1):
+            funcs["obj"] += 100 * (x[i + 1] - x[i] ** 2) ** 2 + (1 - x[i]) ** 2
+
+        fail = False
+        return funcs, fail
+
+    def sens(self, xdict, funcs):
+        self.ng += 1
+        x = xdict["xvars"]
+        funcsSens = {}
+        grads = np.zeros(len(x))
+
+        for i in range(len(x) - 1):
+            grads[i] += 2 * (200 * x[i] ** 3 - 200 * x[i] * x[i + 1] + x[i] - 1)
+            grads[i + 1] += 200 * (x[i + 1] - x[i] ** 2)
+
+        funcsSens["obj"] = {"xvars": grads}
+
+        fail = False
+        return funcsSens, fail
+
+    def optimize(self, optName, tol, optOptions={}, storeHistory=False, hotStart=None):
+        self.nf = 0  # number of function evaluations
+        self.ng = 0  # number of gradient evaluations
+        # Optimization Object
+
+        optProb = Optimization("Rosenbrock Problem", self.objfunc)
+
+        n = 4  # Number of design variables
+        np.random.seed(10)
+        value = np.random.normal(size=n)
+
+        lower = np.ones(n) * -50
+        upper = np.ones(n) * 50
+        optProb.addVarGroup("xvars", n, lower=lower, upper=upper, value=value)
+
+        # Objective
+        optProb.addObj("obj")
+
+        # Check optimization problem:
+        print(optProb)
+
+        # Optimizer
+        try:
+            opt = OPT(optName, options=optOptions)
+        except Error:
+            raise unittest.SkipTest("Optimizer not available:", optName)
+
+        # Solution
+        if storeHistory is not None:
+            if storeHistory is True:
+                self.histFileName = "%s_Rsbrk_Hist.hst" % (optName.lower())
+            elif isinstance(storeHistory, str):
+                self.histFileName = storeHistory
+        else:
+            self.histFileName = None
+
+        sol = opt(optProb, sens=self.sens, storeHistory=self.histFileName, hotStart=hotStart)
+
+        # Test printing solution to screen
+        print(sol)
+
+        # Check Solution
+        self.fStar1 = 0.0
+
+        self.xStar1 = np.ones(n)
+
+        dv = sol.getDVs()
+        sol_xvars = [sol.variables["xvars"][i].value for i in range(n)]
+
+        assert_allclose(sol_xvars, dv["xvars"], atol=tol, rtol=tol)
+
+        assert_allclose(sol.objectives["obj"].value, self.fStar1, atol=tol, rtol=tol)
+        assert_allclose(dv["xvars"], self.xStar1, atol=tol, rtol=tol)
+
+    def check_hist_file(self, optimizer, tol):
+        """
+        We check the history file here along with the API
+        """
+        hist = History(self.histFileName, flag="r")
+        # Metadata checks
+        metadata = hist.getMetadata()
+        self.assertEqual(metadata["optimizer"], optimizer)
+        metadata_def_keys = ["optName", "optOptions", "nprocs", "startTime", "endTime", "optTime", "version"]
+        for key in metadata_def_keys:
+            self.assertIn(key, metadata)
+        hist.getOptProb()
+
+        # Info checks
+        self.assertEqual(hist.getDVNames(), ["xvars"])
+        self.assertEqual(hist.getObjNames(), ["obj"])
+        dvInfo = hist.getDVInfo()
+        self.assertEqual(len(dvInfo), 1)
+        self.assertEqual(dvInfo["xvars"], hist.getDVInfo(key="xvars"))
+        conInfo = hist.getConInfo()
+        self.assertEqual(len(conInfo), 0)
+        objInfo = hist.getObjInfo()
+        self.assertEqual(len(objInfo), 1)
+        self.assertEqual(objInfo["obj"], hist.getObjInfo(key="obj"))
+        for key in ["lower", "upper", "scale"]:
+            self.assertIn(key, dvInfo["xvars"])
+        self.assertIn("scale", objInfo["obj"])
+
+        # callCounter checks
+        callCounters = hist.getCallCounters()
+        last = hist.read("last")  # 'last' key should be present
+        self.assertIn(last, callCounters)
+
+        # iterKey checks
+        iterKeys = hist.getIterKeys()
+        for key in ["xuser", "fail", "isMajor"]:
+            self.assertIn(key, iterKeys)
+
+        # this check is only used for optimizers that guarantee '0' and 'last' contain funcs
+        if optimizer in ["SNOPT", "SLSQP", "PSQP"]:
+            val = hist.getValues(callCounters=["0", "last"], stack=True)
+            self.assertEqual(val["isMajor"].size, 2)
+            self.assertTrue(val["isMajor"][0])  # the first callCounter must be a major iteration
+            self.assertTrue(val["isMajor"][-1])  # the last callCounter must be a major iteration
+            # check optimum stored in history file against xstar
+            assert_allclose(val["xuser"][-1], self.xStar1, atol=tol, rtol=tol)
+
+    def optimize_with_hotstart(self, optName, tol, optOptions={}):
+        """
+        This code will perform 4 optimizations, one real opt and three restarts.
+        In this process, it will check various combinations of storeHistory and hotStart filenames.
+        It will also call `check_hist_file` after the first optimization.
+        """
+
+        self.optimize(optName, tol, storeHistory=True, optOptions=optOptions)
+        self.assertGreater(self.nf, 0)
+        self.assertGreater(self.ng, 0)
+        self.check_hist_file(optName, tol)
+
+        # re-optimize with hotstart
+        self.optimize(optName, tol, storeHistory=False, hotStart=self.histFileName, optOptions=optOptions)
+        # we should have zero actual function/gradient evaluations
+        self.assertEqual(self.nf, 0)
+        self.assertEqual(self.ng, 0)
+        # another test with hotstart, this time with storeHistory = hotStart
+        self.optimize(optName, tol, storeHistory=True, hotStart=self.histFileName, optOptions=optOptions)
+        # we should have zero actual function/gradient evaluations
+        self.assertEqual(self.nf, 0)
+        self.assertEqual(self.ng, 0)
+        # final test with hotstart, this time with a different storeHistory
+        self.optimize(
+            optName,
+            tol,
+            storeHistory="{}_new_hotstart.hst".format(optName),
+            hotStart=self.histFileName,
+            optOptions=optOptions,
+        )
+        # we should have zero actual function/gradient evaluations
+        self.assertEqual(self.nf, 0)
+        self.assertEqual(self.ng, 0)
+
+    def test_snopt(self):
+        test_name = "Rsbrk_SNOPT"
+        store_vars = ["step", "merit", "feasibility", "optimality", "penalty", "Hessian", "condZHZ", "slack", "lambda"]
+        optOptions = {
+            "Save major iteration variables": store_vars,
+            "Print file": "{}.out".format(test_name),
+            "Summary file": "{}_summary.out".format(test_name),
+        }
+        self.optimize_with_hotstart("SNOPT", 1e-8, optOptions=optOptions)
+
+        hist = History(self.histFileName, flag="r")
+        data = hist.getValues(callCounters=["last"])
+        keys = hist.getIterKeys()
+        self.assertIn("isMajor", keys)
+        self.assertEqual(36, data["nMajor"])
+        for var in store_vars:
+            self.assertIn(var, data.keys())
+        self.assertEqual(data["Hessian"].shape, (1, 4, 4))
+        self.assertEqual(data["feasibility"].shape, (1, 1))
+        self.assertEqual(data["slack"].shape, (1, 1))
+        self.assertEqual(data["lambda"].shape, (1, 1))
+
+    def test_slsqp(self):
+        optOptions = {"ACC": 1e-10, "IFILE": "Rsbrk_SLSQP.out"}
+        self.optimize_with_hotstart("SLSQP", 1e-6, optOptions=optOptions)
+
+    def test_nlpqlp(self):
+        optOptions = {"accuracy": 1e-10, "iFile": "Rsbrk_NLPQLP.out"}
+        self.optimize_with_hotstart("NLPQLP", 1e-6, optOptions=optOptions)
+
+    def test_ipopt(self):
+        optOptions = {"output_file": "Rsbrk_IPOPT.out"}
+        self.optimize_with_hotstart("IPOPT", 1e-6, optOptions=optOptions)
+
+    def test_paropt(self):
+        optOptions = {"output_file": "Rsbrk_ParOpt.out"}
+        self.optimize_with_hotstart("ParOpt", 1e-8, optOptions=optOptions)
+
+    def test_conmin(self):
+        optOptions = {
+            "DELFUN": 1e-10,
+            "DABFUN": 1e-10,
+            "IFILE": "Rsbrk_CONMIN.out",
+        }
+        self.optimize_with_hotstart("CONMIN", 1e-9, optOptions=optOptions)
+
+    def test_psqp(self):
+        optOptions = {"IFILE": "Rsbrk_PSQP.out"}
+        self.optimize_with_hotstart("PSQP", 1e-8, optOptions=optOptions)
+
+
+if __name__ == "__main__":
+    unittest.main()