Added Problem.model() methods

Author: MichaelClerx

CHANGELOG.md

@@ -6,7 +6,7 @@ All notable changes to this project will be documented in this file.
 ## Unreleased
 
 ### Added
-- [#1715](https://github.com/pints-team/pints/pull/1715) Added `ProblemErrorMeasure.problem()`, `ProblemLogLikelihood.problem()`
+- [#1715](https://github.com/pints-team/pints/pull/1715) Added methods `ProblemErrorMeasure.problem()`, `ProblemLogLikelihood.problem()`, `SingleOutputProblem.model()` and `MultiOutputProblem.model()`.
 ### Changed
 - [#1713](https://github.com/pints-team/pints/pull/1713) PINTS now requires matplotlib 2.2 or newer.
 ### Deprecated

pints/_core.py

@@ -170,10 +170,12 @@ def evaluateS1(self, parameters):
             np.asarray(dy).reshape((self._n_times, self._n_parameters))
         )
 
+    def model(self):
+        """ Returns the :class:`ForwardModel` underlying this problem. """
+        return self._model
+
     def n_outputs(self):
-        """
-        Returns the number of outputs for this problem (always 1).
-        """
+        """ Returns the number of outputs for this problem (always 1). """
         return 1
 
     def n_parameters(self):
@@ -281,6 +283,10 @@ def evaluateS1(self, parameters):
                 self._n_times, self._n_outputs, self._n_parameters)
         )
 
+    def model(self):
+        """ Returns the :class:`ForwardModel` underlying this problem. """
+        return self._model
+
     def n_outputs(self):
         """
         Returns the number of outputs for this problem.

pints/tests/test_multi_output_problem.py

@@ -35,6 +35,7 @@ def test_basics(self):
         self.assertEqual(problem.n_parameters(), model.n_parameters(), 2)
         self.assertEqual(problem.n_outputs(), model.n_outputs(), 3)
         self.assertEqual(problem.n_times(), len(times))
+        self.assertIs(problem.model(), model)
 
         # Test errors
         times[0] = -2

pints/tests/test_single_output_problem.py

@@ -32,6 +32,7 @@ def test_basics(self):
         self.assertEqual(problem.n_parameters(), model.n_parameters(), 2)
         self.assertEqual(problem.n_outputs(), model.n_outputs(), 1)
         self.assertEqual(problem.n_times(), len(times))
+        self.assertIs(problem.model(), model)
 
         # Test errors
         times[0] = -2