Merge pull request #7766 from RussTedrake/py_pendulum

initial bindings for pendulum example

bindings/pydrake/BUILD.bazel

@@ -137,6 +137,7 @@ PYBIND_LIBRARIES = adjust_labels_for_drake_hoist([
     ":parsers_py",
     ":rbtree_py",
     ":symbolic_py",
+    "//drake/bindings/pydrake/examples",
     "//drake/bindings/pydrake/solvers",
     "//drake/bindings/pydrake/systems",
     "//drake/bindings/pydrake/util",

bindings/pydrake/examples/BUILD.bazel

@@ -0,0 +1,89 @@
+# -*- python -*-
+
+load("@drake//tools/install:install.bzl", "install")
+load("//tools/lint:lint.bzl", "add_lint_tests")
+load(
+    "//tools/skylark:pybind.bzl",
+    "drake_pybind_library",
+    "get_drake_pybind_installs",
+    "get_pybind_package_info",
+)
+load(
+    "//tools/skylark:drake_py.bzl",
+    "drake_py_binary",
+    "drake_py_library",
+    "drake_py_test",
+)
+load(
+    "//tools/skylark:6996.bzl",
+    "adjust_label_for_drake_hoist",
+    "adjust_labels_for_drake_hoist",
+)
+
+package(default_visibility = adjust_labels_for_drake_hoist([
+    "//drake/bindings/pydrake:__subpackages__",
+]))
+
+# This determines how `PYTHONPATH` is configured, and how to install the
+# bindings.
+PACKAGE_INFO = get_pybind_package_info(
+    base_package = adjust_label_for_drake_hoist("//drake/bindings"),
+)
+
+# @note Symbols are NOT imported directly into
+# `__init__.py` to simplify dependency management, meaning that
+# classes are organized by their directory structure rather than
+# by C++ namespace.
+drake_py_library(
+    name = "module_py",
+    srcs = ["__init__.py"],
+    imports = PACKAGE_INFO.py_imports,
+    deps = [
+        "//drake/bindings/pydrake:common_py",
+    ],
+)
+
+drake_pybind_library(
+    name = "pendulum_py",
+    cc_deps = [
+        "//drake/examples/pendulum:pendulum_plant",
+    ],
+    cc_so_name = "pendulum",
+    cc_srcs = ["pendulum_py.cc"],
+    package_info = PACKAGE_INFO,
+    py_deps = [
+        ":module_py",
+    ],
+)
+
+PYBIND_LIBRARIES = [
+    ":pendulum_py",
+]
+
+PY_LIBRARIES = [
+    ":module_py",
+]
+
+drake_py_library(
+    name = "examples",
+    imports = PACKAGE_INFO.py_imports,
+    deps = PYBIND_LIBRARIES + PY_LIBRARIES,
+)
+
+install(
+    name = "install",
+    targets = PY_LIBRARIES,
+    py_dest = PACKAGE_INFO.py_dest,
+    deps = get_drake_pybind_installs(PYBIND_LIBRARIES),
+)
+
+drake_py_test(
+    name = "pendulum_test",
+    size = "small",
+    deps = [
+        ":pendulum_py",
+        "//drake/bindings/pydrake/systems",
+    ],
+)
+
+add_lint_tests()

bindings/pydrake/examples/__init__.py

@@ -0,0 +1 @@
+# Blank Python module.

bindings/pydrake/examples/pendulum_py.cc

@@ -0,0 +1,29 @@
+#include <pybind11/eigen.h>
+#include <pybind11/pybind11.h>
+
+#include "drake/examples/pendulum/pendulum_plant.h"
+
+namespace py = pybind11;
+
+using std::make_unique;
+using std::unique_ptr;
+using std::vector;
+
+PYBIND11_MODULE(pendulum, m) {
+  // NOLINTNEXTLINE(build/namespaces): Emulate placement in namespace.
+  using namespace drake;
+  // NOLINTNEXTLINE(build/namespaces): Emulate placement in namespace.
+  using namespace drake::systems;
+  // NOLINTNEXTLINE(build/namespaces): Emulate placement in namespace.
+  using namespace drake::examples::pendulum;
+
+  m.doc() = "Bindings for the Pendulum example.";
+
+  // TODO(eric.cousineau): At present, we only bind doubles.
+  // In the future, we will bind more scalar types, and enable scalar
+  // conversion.
+  using T = double;
+
+  py::class_<PendulumPlant<T>, LeafSystem<T>>(m, "PendulumPlant")
+    .def(py::init<>());
+}

bindings/pydrake/examples/test/pendulum_test.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+
+import copy
+import unittest
+import numpy as np
+
+import pydrake.systems.framework as framework
+from pydrake.examples.pendulum import (
+    PendulumPlant,
+    )
+from pydrake.systems.analysis import (
+    Simulator
+    )
+from pydrake.systems.primitives import (
+    ConstantVectorSource,
+    )
+
+
+class TestPendulum(unittest.TestCase):
+    def test_simulation(self):
+        # Basic constant-torque pendulum simulation.
+
+        builder = framework.DiagramBuilder()
+
+        pendulum = builder.AddSystem(PendulumPlant())
+        source = builder.AddSystem(ConstantVectorSource([1.0]))
+
+        builder.Connect(source.get_output_port(0),
+                        pendulum.get_input_port(0))
+
+        diagram = builder.Build()
+        simulator = Simulator(diagram)
+        simulator.Initialize()
+
+        # TODO(russt): Clean up state vector access below.
+        state = simulator.get_mutable_context().get_mutable_state()\
+                         .get_mutable_continuous_state().get_mutable_vector()
+
+        initial_state = np.array([1.0, 0.0])
+        state.SetFromVector(initial_state)
+
+        simulator.StepTo(1.0)
+
+        self.assertFalse((state.CopyToVector() == initial_state).all())
+
+
+if __name__ == '__main__':
+    unittest.main()