Module for reading grid from file

src/scf/xc/grid_from_file.cpp

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2025 NWChemEx-Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "xc.hpp"
+#include <filesystem>
+#include <simde/integration_grids/molecular_grid.hpp>
+#include <sstream>
+
+namespace scf::xc {
+namespace {
+const auto desc = R"(
+
+GridFromFile
+------------
+
+Reads a grid from a file. The file is expected to be a text file with four
+columns: x, y, z, weight. Each row of the file corresponds to a grid point.
+The columns should be space separated. An example of the file format is:
+
+.. code-block:: text
+
+    1.0 2.0 3.0 4.0
+    5.0 6.0 7.0 8.0
+
+This would create two grid points: (1.0, 2.0, 3.0) with weight 4.0 and
+(5.0, 6.0, 7.0) with weight 8.0.
+)";
+
+}
+
+using pt = simde::MolecularGrid;
+
+MODULE_CTOR(GridFromFile) {
+    satisfies_property_type<pt>();
+
+    add_input<std::filesystem::path>("Path to Grid File");
+
+    description(desc);
+}
+
+MODULE_RUN(GridFromFile) {
+    // const auto& [molecule] = pt::unwrap_inputs(inputs);
+
+    const auto& path =
+      inputs.at("Path to Grid File").value<std::filesystem::path>();
+
+    std::ifstream file(path);
+    if(!file.is_open()) {
+        throw std::runtime_error("Unable to open file: " + path.string());
+    }
+
+    // Create the grid
+    std::string line;
+    std::vector<chemist::GridPoint> grid_points;
+    while(std::getline(file, line)) {
+        auto first_character = line.find_first_not_of(" \t\r\n");
+        if(first_character == std::string::npos) continue;
+        double x, y, z, weight;
+        std::stringstream ss(line);
+        if(!(ss >> x >> y >> z >> weight) || !(ss >> std::ws).eof()) {
+            throw std::runtime_error("Malformed grid file line: '" + line +
+                                     "'");
+        }
+        grid_points.emplace_back(weight, x, y, z);
+    }
+    chemist::Grid grid(grid_points.begin(), grid_points.end());
+
+    file.close();
+
+    // Return the grid
+    auto rv = results();
+    return pt::wrap_results(rv, std::move(grid));
+}
+} // namespace scf::xc

src/scf/xc/xc.cpp

@@ -18,7 +18,10 @@
 #include "xc.hpp"
 
 namespace scf::xc {
-void load_modules(pluginplay::ModuleManager& mm) { gauxc::load_modules(mm); }
+void load_modules(pluginplay::ModuleManager& mm) {
+    gauxc::load_modules(mm);
+    mm.add_module<GridFromFile>("Grid From File");
+}
 
 void set_defaults(pluginplay::ModuleManager& mm) { gauxc::set_defaults(mm); }
 } // namespace scf::xc

src/scf/xc/xc.hpp

@@ -19,6 +19,8 @@
 
 namespace scf::xc {
 
+DECLARE_MODULE(GridFromFile);
+
 void set_defaults(pluginplay::ModuleManager& mm);
 void load_modules(pluginplay::ModuleManager& mm);
 

tests/cxx/unit_tests/xc/grid_from_file.cpp

@@ -0,0 +1,111 @@
+/*
+ * Copyright 2025 NWChemEx-Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "../../test_scf.hpp"
+#include <iostream>
+#include <pluginplay/pluginplay.hpp>
+
+using namespace scf;
+
+using pt = simde::MolecularGrid;
+
+TEST_CASE("GridFromFile") {
+    pluginplay::ModuleManager mm;
+    scf::load_modules(mm);
+    auto& mod = mm.at("Grid From File");
+
+    auto h2 = test_scf::make_h2<chemist::Molecule>();
+
+    SECTION("file doesn't exist") {
+        std::filesystem::path p = "non_existent_file.txt";
+        mod.change_input("Path to Grid File", p);
+        REQUIRE_THROWS_AS(mod.run_as<pt>(h2), std::runtime_error);
+    }
+
+    SECTION("only three points") {
+        std::filesystem::path p = "unit_test_pretend_h2_grid.txt";
+        std::ofstream file(p);
+        file << "1.0 2.0 3.0\n";
+        file << "5.0 6.0 7.0 8.0\n";
+        file.close();
+        mod.change_input("Path to Grid File", p);
+        REQUIRE_THROWS_AS(mod.run_as<pt>(h2), std::runtime_error);
+        std::filesystem::remove(p);
+    }
+
+    SECTION("five numbers points") {
+        std::filesystem::path p = "unit_test_pretend_h2_grid.txt";
+        std::ofstream file(p);
+        file << "1.0 2.0 3.0 4.0 5.0\n";
+        file << "5.0 6.0 7.0 8.0\n";
+        file.close();
+        mod.change_input("Path to Grid File", p);
+        REQUIRE_THROWS_AS(mod.run_as<pt>(h2), std::runtime_error);
+        std::filesystem::remove(p);
+    }
+
+    SECTION("non-mumeric data") {
+        std::filesystem::path p = "unit_test_pretend_h2_grid.txt";
+        std::ofstream file(p);
+        file << "1.0 2.0 3.0 hello\n";
+        file << "5.0 6.0 7.0 8.0\n";
+        file.close();
+        mod.change_input("Path to Grid File", p);
+        REQUIRE_THROWS_AS(mod.run_as<pt>(h2), std::runtime_error);
+        std::filesystem::remove(p);
+    }
+
+    SECTION("good file") {
+        std::filesystem::path p = "unit_test_pretend_h2_grid.txt";
+        std::ofstream file(p);
+        file << "1.0 2.0 3.0 4.0\n";
+        file << "5.0 6.0 7.0 8.0\n";
+        file.close();
+        mod.change_input("Path to Grid File", p);
+        auto grid = mod.run_as<pt>(h2);
+        REQUIRE(grid.size() == 2);
+        REQUIRE(grid.at(0).weight() == 4.0);
+        REQUIRE(grid.at(0).point().x() == 1.0);
+        REQUIRE(grid.at(0).point().y() == 2.0);
+        REQUIRE(grid.at(0).point().z() == 3.0);
+        REQUIRE(grid.at(1).weight() == 8.0);
+        REQUIRE(grid.at(1).point().x() == 5.0);
+        REQUIRE(grid.at(1).point().y() == 6.0);
+        REQUIRE(grid.at(1).point().z() == 7.0);
+        std::filesystem::remove(p);
+    }
+
+    SECTION("skip blank line") {
+        std::filesystem::path p = "unit_test_pretend_h2_grid.txt";
+        std::ofstream file(p);
+        file << "1.0 2.0 3.0 4.0\n";
+        file << "\n";
+        file << "5.0 6.0 7.0 8.0\n";
+        file.close();
+        mod.change_input("Path to Grid File", p);
+        auto grid = mod.run_as<pt>(h2);
+        REQUIRE(grid.size() == 2);
+        REQUIRE(grid.at(0).weight() == 4.0);
+        REQUIRE(grid.at(0).point().x() == 1.0);
+        REQUIRE(grid.at(0).point().y() == 2.0);
+        REQUIRE(grid.at(0).point().z() == 3.0);
+        REQUIRE(grid.at(1).weight() == 8.0);
+        REQUIRE(grid.at(1).point().x() == 5.0);
+        REQUIRE(grid.at(1).point().y() == 6.0);
+        REQUIRE(grid.at(1).point().z() == 7.0);
+        std::filesystem::remove(p);
+    }
+}