Merge pull request #7590 from EricCousineau-TRI/feature/py_systems_pr1

Add preliminary Python bindings and examples for systems framework.

WORKSPACE

@@ -280,8 +280,8 @@ github_archive(
 github_archive(
     name = "pybind11",
     repository = "RobotLocomotion/pybind11",
-    commit = "ffcf754ae9e766632610975d22372a86a7b63014",
-    sha256 = "7cd6f4efb02bf9ae17eeb2afba68023af913e61ae76e8b4254203d0eec019525",  # noqa
+    commit = "48999b69bde29cdf8d616d4fbd3d6ab1c561027d",
+    sha256 = "2ea18adfb608948cab1b5978081dc8c318ed47573ccd66f1603a37fbdbfc56da",  # noqa
     build_file = "tools/workspace/pybind11/pybind11.BUILD.bazel",
 )
 

bindings/pydrake/BUILD.bazel

@@ -116,13 +116,16 @@ PYBIND_LIBRARIES = adjust_labels_for_drake_hoist([
     ":rbtree_py",
     ":symbolic_py",
     "//drake/bindings/pydrake/solvers",
+    "//drake/bindings/pydrake/systems",
 ])
 
+PY_LIBRARIES = [
+    ":util_py",
+]
+
 install(
     name = "install",
-    targets = [
-        ":util_py",
-    ],
+    targets = PY_LIBRARIES,
     py_dest = get_pybind_library_dest(),
     visibility = ["//visibility:public"],
     deps = get_drake_pybind_installs(PYBIND_LIBRARIES),
@@ -131,7 +134,7 @@ install(
 drake_py_library(
     name = "pydrake",
     visibility = ["//visibility:public"],
-    deps = PYBIND_LIBRARIES,
+    deps = PYBIND_LIBRARIES + PY_LIBRARIES,
 )
 
 # Test ODR (One Definition Rule).

bindings/pydrake/solvers/BUILD.bazel

@@ -81,18 +81,18 @@ PYBIND_LIBRARIES = [
     ":mosek_py",
 ]
 
+PY_LIBRARIES = [
+    ":module_py",
+]
+
 drake_py_library(
     name = "solvers",
-    deps = PYBIND_LIBRARIES + [
-        ":module_py",
-    ],
+    deps = PYBIND_LIBRARIES + PY_LIBRARIES,
 )
 
 install(
     name = "install",
-    targets = [
-        ":module_py",
-    ],
+    targets = PY_LIBRARIES,
     py_dest = get_pybind_library_dest(),
     deps = get_drake_pybind_installs(PYBIND_LIBRARIES),
 )

bindings/pydrake/solvers/__init__.py

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

bindings/pydrake/systems/BUILD.bazel

@@ -0,0 +1,167 @@
+# -*- 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_library_dest",
+)
+load(
+    "//tools/skylark:drake_py.bzl",
+    "drake_py_binary",
+    "drake_py_library",
+    "drake_py_test",
+)
+load("//tools/skylark:6996.bzl", "adjust_labels_for_drake_hoist")
+
+package(default_visibility = adjust_labels_for_drake_hoist([
+    "//drake/bindings/pydrake:__subpackages__",
+]))
+
+# @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. If you want all symbols, use `all.py`.
+drake_py_library(
+    name = "module_py",
+    srcs = ["__init__.py"],
+    deps = [
+        "//drake/bindings/pydrake:common_py",
+    ],
+)
+
+drake_pybind_library(
+    name = "framework_py",
+    cc_so_name = "framework",
+    cc_srcs = ["framework_py.cc"],
+    py_deps = [
+        ":module_py",
+    ],
+)
+
+drake_pybind_library(
+    name = "primitives_py",
+    cc_so_name = "primitives",
+    cc_srcs = ["primitives_py.cc"],
+    py_deps = [
+        ":framework_py",
+        ":module_py",
+    ],
+)
+
+drake_pybind_library(
+    name = "analysis_py",
+    cc_so_name = "analysis",
+    cc_srcs = ["analysis_py.cc"],
+    py_deps = [
+        ":framework_py",
+        ":module_py",
+    ],
+)
+
+drake_py_library(
+    name = "drawing_py",
+    srcs = ["drawing.py"],
+    deps = [":module_py"],
+    # TODO(eric.cousineau): Expose information to allow `imports = ...` to be
+    # defined, rather than rely on `module_py`.
+)
+
+drake_py_library(
+    name = "all_py",
+    deps = [
+        ":analysis_py",
+        ":drawing_py",
+        ":framework_py",
+        ":primitives_py",
+    ],
+)
+
+PYBIND_LIBRARIES = [
+    ":analysis_py",
+    ":framework_py",
+    ":primitives_py",
+]
+
+PY_LIBRARIES = [
+    ":all_py",
+    ":drawing_py",
+    ":module_py",
+]
+
+drake_py_library(
+    name = "systems",
+    deps = PYBIND_LIBRARIES + PY_LIBRARIES,
+)
+
+install(
+    name = "install",
+    targets = PY_LIBRARIES,
+    py_dest = get_pybind_library_dest(),
+    deps = get_drake_pybind_installs(PYBIND_LIBRARIES),
+)
+
+drake_py_test(
+    name = "general_test",
+    size = "small",
+    deps = [
+        ":analysis_py",
+        ":framework_py",
+        ":primitives_py",
+    ],
+)
+
+# TODO(eric.cousineau): Convert this to a workflow test once `pydot` is added
+# to `install_prereqs.sh`.
+drake_py_binary(
+    name = "graphviz_example",
+    srcs = ["test/graphviz_example.py"],
+    deps = [
+        ":drawing_py",
+        ":framework_py",
+        ":primitives_py",
+    ],
+)
+
+drake_pybind_library(
+    name = "lifetime_test_util",
+    testonly = 1,
+    add_install = False,
+    cc_so_name = "test/lifetime_test_util",
+    cc_srcs = ["test/lifetime_test_util_py.cc"],
+    py_deps = [
+        ":primitives_py",
+    ],
+)
+
+drake_py_test(
+    name = "lifetime_test",
+    deps = [
+        ":analysis_py",
+        ":framework_py",
+        ":lifetime_test_util",
+        ":primitives_py",
+    ],
+)
+
+drake_py_test(
+    name = "custom_test",
+    size = "small",
+    deps = [
+        ":analysis_py",
+        ":framework_py",
+        ":primitives_py",
+    ],
+)
+
+drake_py_test(
+    name = "vector_test",
+    size = "small",
+    deps = [
+        ":framework_py",
+    ],
+)
+
+add_lint_tests()

bindings/pydrake/systems/__init__.py

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

bindings/pydrake/systems/all.py

@@ -0,0 +1,8 @@
+from .analysis import *
+from .framework import *
+from .primitives import *
+
+try:
+    from .drawing import *
+except ImportError:
+    pass

bindings/pydrake/systems/analysis_py.cc

@@ -0,0 +1,26 @@
+#include <pybind11/pybind11.h>
+
+#include "drake/systems/analysis/simulator.h"
+
+namespace py = pybind11;
+
+using std::unique_ptr;
+
+PYBIND11_MODULE(analysis, m) {
+  // NOLINTNEXTLINE(build/namespaces): Emulate placement in namespace.
+  using namespace drake::systems;
+
+  auto py_iref = py::return_value_policy::reference_internal;
+
+  m.doc() = "Bindings for the analysis portion of the Systems framework.";
+
+  using T = double;
+
+  py::class_<Simulator<T>>(m, "Simulator")
+    .def(py::init<const System<T>&>())
+    .def(py::init<const System<T>&, unique_ptr<Context<T>>>())
+    .def("Initialize", &Simulator<T>::Initialize)
+    .def("StepTo", &Simulator<T>::StepTo)
+    .def("get_context", &Simulator<T>::get_context, py_iref)
+    .def("get_mutable_context", &Simulator<T>::get_mutable_context, py_iref);
+}

bindings/pydrake/systems/drawing.py

@@ -0,0 +1,40 @@
+"""
+Provides general visualization utilities. This is NOT related to `rendering`.
+@note This is an optional module, dependent on `pydot` and `matplotlib` being
+installed.
+"""
+
+from StringIO import StringIO
+
+import matplotlib.image as mpimg
+import matplotlib.pyplot as plt
+import pydot
+
+
+# TODO(eric.cousineau): Move `plot_graphviz` to something more accessible to
+# `call_python_client`.
+
+
+def plot_graphviz(dot_text):
+    """Renders a DOT graph in matplotlib."""
+    # @ref https://stackoverflow.com/a/18522941/7829525
+    # Tried (reason ignored): pydotplus (`pydot` works), networkx
+    # (`read_dot` does not work robustly?), pygraphviz (coupled with
+    # `networkx`).
+    g = pydot.graph_from_dot_data(dot_text)
+    if isinstance(g, list):
+        # Per Ioannis's follow-up comment in the above link, in pydot >= 1.2.3
+        # `graph_from_dot_data` returns a list of graphs.
+        # Handle this case for now.
+        assert len(g) == 1
+        g = g[0]
+    s = StringIO()
+    g.write_png(s)
+    s.seek(0)
+    plt.axis('off')
+    return plt.imshow(plt.imread(s), aspect="equal")
+
+
+def plot_system_graphviz(system):
+    """Renders a System's Graphviz representation in `matplotlib`. """
+    return plot_graphviz(system.GetGraphvizString())