add Matrix slicing

src/storage/matrix.cpp

@@ -54,6 +54,22 @@ void define_sparse_matrix(py::module& m) {
         .def("row_iter", [](storm::storage::SparseMatrix<double>& matrix, row_index start, row_index end) {
                 return py::make_iterator(matrix.begin(start), matrix.end(end));
             }, py::keep_alive<0, 1>() /* keep object alive while iterator exists */, py::arg("row_start"), py::arg("row_end"), "Get iterator from start to end")
+
+        // (partial) container interface to allow e.g. matrix[7:9]
+        .def("__len__", &storm::storage::SparseMatrix<double>::getRowCount)
+        .def("__getitem__", [](storm::storage::SparseMatrix<double>& matrix, entry_index i) {
+            if (i >= matrix.getRowCount())
+                throw py::index_error();
+            return matrix.getRows(i, i+1);
+        }, py::return_value_policy::reference, py::keep_alive<1, 0>())
+        .def("__getitem__", [](storm::storage::SparseMatrix<double>& matrix, py::slice slice) {
+                size_t start, stop, step, slice_length;
+                if (!slice.compute(matrix.getRowCount(), &start, &stop, &step, &slice_length))
+                    throw py::error_already_set();
+                if (step != 1)
+                    throw py::value_error(); // not supported
+                return matrix.getRows(start, stop);
+            }, py::return_value_policy::reference, py::keep_alive<1, 0>())
     ;
 
     py::class_<storm::storage::SparseMatrix<storm::RationalFunction>>(m, "ParametricSparseMatrix", "Parametric sparse matrix")
@@ -83,6 +99,22 @@ void define_sparse_matrix(py::module& m) {
         .def("row_iter", [](storm::storage::SparseMatrix<storm::RationalFunction>& matrix, parametric_row_index start, parametric_row_index end) {
                 return py::make_iterator(matrix.begin(start), matrix.end(end));
             }, py::keep_alive<0, 1>() /* keep object alive while iterator exists */, py::arg("row_start"), py::arg("row_end"), "Get iterator from start to end")
+
+        // (partial) container interface to allow e.g. matrix[7:9]
+        .def("__len__", &storm::storage::SparseMatrix<storm::RationalFunction>::getRowCount)
+        .def("__getitem__", [](storm::storage::SparseMatrix<storm::RationalFunction>& matrix, parametric_entry_index i) {
+            if (i >= matrix.getRowCount())
+                throw py::index_error();
+            return matrix.getRows(i, i+1);
+        }, py::return_value_policy::reference, py::keep_alive<1, 0>())
+        .def("__getitem__", [](storm::storage::SparseMatrix<storm::RationalFunction>& matrix, py::slice slice) {
+            size_t start, stop, step, slice_length;
+            if (!slice.compute(matrix.getRowCount(), &start, &stop, &step, &slice_length))
+                throw py::error_already_set();
+            if (step != 1)
+                throw py::value_error(); // not supported
+            return matrix.getRows(start, stop);
+        }, py::return_value_policy::reference, py::keep_alive<1, 0>())
     ;
 
     // Rows