systems/cleanup: Change context.FixInputPort() to port.FixValue()

systems/analysis/test/lyapunov_test.cc

@@ -71,7 +71,7 @@ VectorX<T> pendulum_bases(const VectorX<T>& x) {
 GTEST_TEST(LyapunovTest, PendulumSampleBasedLyapunov) {
   examples::pendulum::PendulumPlant<double> pendulum;
   auto context = pendulum.CreateDefaultContext();
-  context->FixInputPort(0, Vector1d{0.0});
+  pendulum.get_input_port().FixValue(context.get(), 0.0);
 
   Eigen::VectorXd q_samples =
       Eigen::VectorXd::LinSpaced(31, -1.5 * M_PI, 1.5 * M_PI);

systems/controllers/dynamic_programming.cc

@@ -86,7 +86,7 @@ FittedValueIteration(
     cost[input].resize(num_states);
 
     input_mesh.get_mesh_point(input, &input_vec);
-    context.FixInputPort(0, input_vec);
+    system.get_input_port(0).FixValue(&context, input_vec);
 
     for (int state = 0; state < num_states; state++) {
       context.SetTime(0.0);
@@ -216,7 +216,7 @@ Eigen::VectorXd LinearProgrammingApproximateDynamicProgramming(
   Eigen::VectorXd state_vec(state_size);
   Eigen::VectorXd next_state_vec(state_size);
   for (int input = 0; input < num_inputs; input++) {
-    context.FixInputPort(0, input_samples.col(input));
+    system.get_input_port(0).FixValue(&context, input_samples.col(input));
     for (int state = 0; state < num_states; state++) {
       context.SetTime(0.0);
       state_vec = state_samples.col(state);

systems/controllers/linear_model_predictive_controller.h

@@ -60,7 +60,8 @@ class LinearModelPredictiveController : public LeafSystem<T> {
   /// of dimension num_inputs.
   /// @pre base_context must have discrete states set as appropriate for the
   /// given @p model.  The input must also be initialized via
-  /// `base_context->FixInputPort(0, u0)`, or otherwise initialized via Diagram.
+  /// `input_port.FixValue(base_context, u0)`, or otherwise initialized via
+  /// Diagram.
   LinearModelPredictiveController(
       std::unique_ptr<systems::System<double>> model,
       std::unique_ptr<systems::Context<double>> base_context,

systems/estimators/test/kalman_filter_test.cc

@@ -47,7 +47,7 @@ GTEST_TEST(TestKalman, DoubleIntegrator) {
   // Should get the same result, but as an affine system.
   auto sys = std::make_unique<LinearSystem<double>>(A, B, C, D);
   auto context = sys->CreateDefaultContext();
-  context->FixInputPort(0, Eigen::Matrix<double, 1, 1>::Zero());
+  sys->get_input_port().FixValue(context.get(), 0.0);
   context->get_mutable_continuous_state().SetFromVector(
       Eigen::Vector2d::Zero());
   auto filter =

systems/estimators/test/luenberger_observer_test.cc

@@ -62,8 +62,8 @@ GTEST_TEST(LuenbergerObserverTest, ErrorDynamics) {
 
   Eigen::Vector3d xhatdot = A * xhat + B * u + L * (y - C * xhat - D * u);
 
-  context->FixInputPort(0, y);
-  context->FixInputPort(1, u);
+  observer->get_input_port(0).FixValue(context.get(), y);
+  observer->get_input_port(1).FixValue(context.get(), u);
   context->get_mutable_continuous_state_vector().SetFromVector(xhat);
 
   observer->CalcTimeDerivatives(*context, derivatives.get());

systems/lcm/test/lcm_log_playback_test.cc

@@ -16,14 +16,14 @@ namespace {
 const int kDim = 1;
 
 void SetInput(double time, const std::string& name, double val,
-              Context<double>* context) {
+              const InputPort<double>& input_port, Context<double>* context) {
   lcmt_drake_signal msg;
   msg.dim = kDim;
   msg.val.resize(kDim, val);
   msg.coord.resize(kDim, name);
   msg.timestamp = time * 1e6;
   context->SetTime(time);
-  context->FixInputPort(0, AbstractValue::Make<lcmt_drake_signal>(msg));
+  input_port.FixValue(context, msg);
 }
 
 class DummySys : public LeafSystem<double> {
@@ -92,26 +92,26 @@ void GenerateLog() {
   auto pub1 = LcmPublisherSystem::Make<lcmt_drake_signal>("Ch1", &w_log);
   auto context1 = pub1->CreateDefaultContext();
 
-  SetInput(0.1, "Ch0", 1, context0.get());
+  SetInput(0.1, "Ch0", 1, pub0->get_input_port(), context0.get());
   pub0->Publish(*context0);
 
-  SetInput(0.22, "Ch1", 2, context1.get());
+  SetInput(0.22, "Ch1", 2, pub1->get_input_port(), context1.get());
   pub1->Publish(*context1);
 
   // Testing multiple messages sent to the same channel at the same time.
   // Only the last one should be visible from the Subscriber's point of view.
-  SetInput(0.3, "Ch0", 3, context0.get());
+  SetInput(0.3, "Ch0", 3, pub0->get_input_port(), context0.get());
   pub0->Publish(*context0);
-  SetInput(0.3, "Ch0", 4, context0.get());
+  SetInput(0.3, "Ch0", 4, pub0->get_input_port(), context0.get());
   pub0->Publish(*context0);
-  SetInput(0.3, "Ch0", 5, context0.get());
+  SetInput(0.3, "Ch0", 5, pub0->get_input_port(), context0.get());
   pub0->Publish(*context0);
 
   // Testing sending a message to a different channel at the same time.
-  SetInput(0.3, "Ch1", 6, context1.get());
+  SetInput(0.3, "Ch1", 6, pub1->get_input_port(), context1.get());
   pub1->Publish(*context1);
 
-  SetInput(0.4, "Ch1", 7, context1.get());
+  SetInput(0.4, "Ch1", 7, pub1->get_input_port(), context1.get());
   pub1->Publish(*context1);
 }
 

systems/plants/spring_mass_system/test/spring_mass_system_test.cc

@@ -187,17 +187,13 @@ TEST_F(SpringMassSystemTest, DynamicsWithExternalForce) {
   // Asserts exactly one input for this case expecting an external force.
   ASSERT_EQ(1, context_->num_input_ports());
 
-  // Creates a vector holding the data entry to the supplied input force.
-  auto force_vector = make_unique<BasicVector<double>>(1 /* size */);
-
   // Sets the input force.
   const double kExternalForce = 1.0;
-  force_vector->get_mutable_value() << kExternalForce;
 
   // Creates a free standing input port not actually connected to the output of
-  // another system but that has its own data in force_vector.
+  // another system but that has its own data.
   // This is done in order to be able to test this system standalone.
-  context_->FixInputPort(0, std::move(force_vector));
+  system_->get_input_port(0).FixValue(context_.get(), kExternalForce);
 
   InitializeState(0.1, 0.1);  // Displacement 0.1m, velocity 0.1m/sec.
   system_->CalcTimeDerivatives(*context_, system_derivatives_.get());

systems/trajectory_optimization/direct_collocation.cc

@@ -64,8 +64,9 @@ DirectCollocationConstraint::DirectCollocationConstraint(
     }
 
     // Provide a fixed value for the input port and keep an alias around.
-    input_port_value_ = &context_->FixInputPort(
-        input_port_->get_index(), system_->AllocateInputVector(*input_port_));
+    input_port_value_ = &input_port_->FixValue(
+        context_.get(),
+        system_->AllocateInputVector(*input_port_)->get_value());
   }
 }
 
@@ -169,8 +170,9 @@ DirectCollocation::DirectCollocation(
 
   if (input_port_) {
     // Allocate the input port and keep an alias around.
-    input_port_value_ = &context_->FixInputPort(
-        input_port_->get_index(), system_->AllocateInputVector(*input_port_));
+    input_port_value_ = &input_port_->FixValue(
+        context_.get(),
+        system_->AllocateInputVector(*input_port_)->get_value());
   }
 
   // Add the dynamic constraints.

systems/trajectory_optimization/direct_transcription.cc

@@ -330,8 +330,9 @@ void DirectTranscription::AddAutodiffDynamicConstraints(
     }
 
     // Provide a fixed value for the input port and keep an alias around.
-    input_port_value_ = &context_->FixInputPort(
-        input_port_->get_index(), system_->AllocateInputVector(*input_port_));
+    input_port_value_ = &input_port_->FixValue(
+        context_.get(),
+        system_->AllocateInputVector(*input_port_)->get_value());
   }
 
   // For N-1 timesteps, add a constraint which depends on the knot