Merge pull request #8500 from EricCousineau-TRI/issue/8491

 pydrake symbolic: Disable Formula.__nonzero__

bindings/pydrake/BUILD.bazel

@@ -65,6 +65,7 @@ drake_pybind_library(
     py_deps = [
         ":common_py",
         ":math_py",
+        "//bindings/pydrake/util:deprecation_py",
     ],
     py_srcs = [
         "autodiffutils.py",
@@ -132,6 +133,7 @@ drake_pybind_library(
     py_deps = [
         ":common_py",
         ":math_py",
+        "//bindings/pydrake/util:deprecation_py",
     ],
     py_srcs = ["symbolic.py"],
 )
@@ -280,6 +282,7 @@ drake_py_unittest(
     deps = [
         ":algebra_test_util_py",
         ":symbolic_py",
+        "//bindings/pydrake/util:containers_py",
     ],
 )
 

bindings/pydrake/autodiffutils_py.cc

@@ -17,6 +17,12 @@ namespace pydrake {
 PYBIND11_MODULE(_autodiffutils_py, m) {
   m.doc() = "Bindings for Eigen AutoDiff Scalars";
 
+  // Install NumPy warning filtres.
+  // N.B. This may interfere with other code, but until that is a confirmed
+  // issue, we should agressively try to avoid these warnings.
+  py::module::import("pydrake.util.deprecation")
+      .attr("install_numpy_warning_filters")();
+
   py::class_<AutoDiffXd> autodiff(m, "AutoDiffXd");
   autodiff
     .def(py::init<const double&, const Eigen::VectorXd&>())

bindings/pydrake/symbolic_py.cc

@@ -23,6 +23,12 @@ PYBIND11_MODULE(_symbolic_py, m) {
   // NOLINTNEXTLINE(build/namespaces): Emulate placement in namespace.
   using namespace drake::symbolic;
 
+  // Install NumPy warning filtres.
+  // N.B. This may interfere with other code, but until that is a confirmed
+  // issue, we should agressively try to avoid these warnings.
+  py::module::import("pydrake.util.deprecation")
+      .attr("install_numpy_warning_filters")();
+
   m.doc() =
       "Symbolic variable, variables, monomial, expression, polynomial, and "
       "formula";
@@ -343,7 +349,14 @@ PYBIND11_MODULE(_symbolic_py, m) {
       .def("__hash__",
            [](const Formula& self) { return std::hash<Formula>{}(self); })
       .def_static("True", &Formula::True)
-      .def_static("False", &Formula::False);
+      .def_static("False", &Formula::False)
+      .def("__nonzero__", [](const Formula&) {
+        throw std::runtime_error(
+            "You should not call `__nonzero__` on `Formula`. If you are trying "
+            "to make a map with `Variable`, `Expression`, or `Polynomial` as "
+            "keys and access the keys, please use "
+            "`pydrake.util.containers.EqualToDict`.");
+      });
 
   // Cannot overload logical operators: http://stackoverflow.com/a/471561
   // Defining custom function for clarity.