Adds CPP implementatinon

CMakeLists.txt

@@ -1,9 +1,20 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.11)
 
 project(EsriAssignment)
 
 set(CMAKE_CXX_STANDARD 17)
 
+include(FetchContent)
+
+FetchContent_Declare(json
+  GIT_REPOSITORY https://github.com/ArthurSonzogni/nlohmann_json_cmake_fetchcontent
+  GIT_TAG v3.9.1)
+FetchContent_GetProperties(json)
+if(NOT json_POPULATED)
+  FetchContent_Populate(json)
+  add_subdirectory(${json_SOURCE_DIR} ${json_BINARY_DIR} EXCLUDE_FROM_ALL)
+endif()
+
 find_package(Protobuf REQUIRED)
 include_directories(${PROTOBUF_INCLUDE_DIR})
 include_directories(${CMAKE_CURRENT_BINARY_DIR})
@@ -11,4 +22,3 @@ include_directories(${CMAKE_CURRENT_BINARY_DIR})
 add_subdirectory(protocol_buffers_definitions)
 include_directories(src)
 add_subdirectory(src)
-

src/CMakeLists.txt

@@ -1,6 +1,10 @@
 
 set(assignment_SOURCES
-  main.cpp)
+  main.cpp
+  calc.cpp
+  json_output.cpp
+  proto_loader.cpp)
 
 add_executable(main ${assignment_SOURCES})
-target_link_libraries(main proto ${PROTOBUF_LIBRARY})
+target_link_libraries(main PRIVATE proto ${PROTOBUF_LIBRARY})
+target_link_libraries(main PRIVATE nlohmann_json::nlohmann_json)

src/calc.cpp

@@ -0,0 +1,70 @@
+#include "calc.hpp"
+#include <algorithm>
+
+
+namespace calc {
+
+
+std::pair<Position, Position>
+position_segment(std::vector<Position> const& position, double time)
+{
+  auto second = std::lower_bound(position.begin(), position.end(), time,
+    [](Position const& pos, double t) {
+      return pos.time < t;
+    });
+  if (second == position.begin()) { // corner case
+    second++;
+  }
+  return std::make_pair(*(second-1), *second);
+}
+
+
+void interpolate_positions(std::vector<Magnetic>& magnetics, std::vector<Position> const& truth)
+{
+  for (auto& mag : magnetics) {
+    auto const truth_seg = position_segment(truth, mag.time);
+    for (size_t i = 0; i < mag.position.size(); i++) {
+      mag.position[i] =
+        (truth_seg.second.position[i] - truth_seg.first.position[i]) /
+        (truth_seg.second.time - truth_seg.first.time) *
+        (mag.time - truth_seg.first.time) + truth_seg.first.position[i];
+    }
+  }
+}
+
+
+void crop_temporal_inersection(std::vector<Magnetic>& magnetics, std::vector<Position> const& truth)
+{
+  auto const mag_first = std::lower_bound(
+    magnetics.begin(), magnetics.end(), truth[0].time,
+    [](Magnetic const& mag, double t) {
+      return mag.time < t;
+    });
+  magnetics.erase(magnetics.begin(), mag_first);
+  auto const mag_last = std::upper_bound(
+    magnetics.begin(), magnetics.end(), truth.back().time,
+    [](double t, Magnetic const& mag) {
+      return t < mag.time;
+    });
+  magnetics.erase(mag_last, magnetics.end());
+}
+
+
+std::tuple<double, double, double, double>
+spatial_extent(std::vector<Magnetic> const& mag)
+{
+  auto [x_min, x_max] = std::minmax_element(
+    std::cbegin(mag), std::cend(mag),
+    [](Magnetic const& a, Magnetic const& b) {
+      return a.position[0] < b.position[0];
+    });
+  auto [y_min, y_max] = std::minmax_element(
+    std::cbegin(mag), std::cend(mag),
+    [](Magnetic const& a, Magnetic const& b) {
+      return a.position[1] < b.position[1];
+    });
+  return std::make_tuple(x_min->position[0], y_min->position[1], x_max->position[0], y_max->position[1]);
+}
+
+
+}

src/calc.hpp

@@ -0,0 +1,47 @@
+#ifndef CALC_HPP_
+#define CALC_HPP_
+
+#include "data.hpp"
+
+#include <cmath>
+#include <numeric>
+#include <vector>
+
+
+namespace calc {
+
+
+template <typename iter_t>
+double norm(iter_t first, iter_t last)
+{
+  return std::sqrt(std::inner_product(first, last, first, 0.0));
+}
+
+
+std::pair<Position, Position>
+position_segment(std::vector<Position> const& position, double time);
+
+void interpolate_positions(std::vector<Magnetic>& magnetics, std::vector<Position> const& truth);
+void crop_temporal_inersection(std::vector<Magnetic>& magnetics, std::vector<Position> const& truth);
+
+std::tuple<double, double, double, double>
+spatial_extent(std::vector<Magnetic> const& mag);
+
+template<typename grid_t, typename avg_grid_t>
+void average_grid(grid_t& grid, avg_grid_t& average_grid)
+{
+  for (size_t x = 0; x < grid.size_x(); x++) {
+    for (size_t y = 0; y < grid.size_y(); y++) {
+      auto const& cell = grid[x][y];
+      if (cell.size() > 0) {
+        double const sum = std::accumulate(cell.cbegin(), cell.cend(), 0.0);
+        size_t const n = cell.size();
+        average_grid[x][y] = sum / n;
+      }
+    }
+  }
+}
+
+} // namespace calc
+
+#endif // CALC_HPP_

src/data.hpp

@@ -0,0 +1,31 @@
+#ifndef DATA_HPP_
+#define DATA_HPP_
+
+#include <array>
+#include <vector>
+
+using Coordinate = std::array<double, 2>;
+
+
+struct Magnetic {
+  Magnetic(double t, double x, double y, double z) :
+    time(t), field({x, y, z}) {}
+  Magnetic(double t, double x, double y) :
+    time(t), position({x, y}) {}
+  double time;
+  std::array<double, 3> field;
+  Coordinate position;
+};
+
+
+struct Position {
+  Position(double t, double x, double y) :
+    time(t), position({x, y}) {}
+  double time;
+  Coordinate position;
+};
+
+using Magnetics = std::vector<Magnetic>;
+using Positions = std::vector<Position>;
+
+#endif /* DATA_HPP_ */

src/json_output.cpp

@@ -0,0 +1,22 @@
+
+#include "json_output.hpp"
+
+#include <iomanip>
+#include <fstream>
+
+
+JsonOutput::JsonOutput(char const* file_path) :
+  filePath_(file_path)
+{}
+
+
+bool JsonOutput::write()
+{
+  std::ofstream outfile(filePath_);
+  if (!outfile) {
+    return false;
+  }
+  outfile << std::setw(2);
+  outfile << jsonData_ << std::endl;
+  return true;
+}

src/json_output.hpp

@@ -0,0 +1,24 @@
+#ifndef JSONOUTPUT_HPP_
+#define JSONOUTPUT_HPP_
+
+#include <nlohmann/json.hpp>
+
+
+class JsonOutput {
+public:
+  explicit JsonOutput(char const* file_path);
+  ~JsonOutput() = default;
+
+  template<typename T>
+  void add(char const* key, T const& obj)
+  {
+    jsonData_[key] = obj;
+  }
+  bool write();
+
+private:
+  char const* filePath_;
+  ::nlohmann::json jsonData_;
+};
+
+#endif // JSONOUTPUT_HPP_

src/main.cpp

@@ -1,40 +1,107 @@
-#include <fstream>
+#include "calc.hpp"
+#include "json_output.hpp"
+#include "proto_loader.hpp"
+#include "spatial_grid.hpp"
+
 #include <iostream>
-
-#include "protocol_buffers_definitions/recordings.pb.h"
+#include <limits>
+#include <string>
+#include <utility>
+#include <vector>
 
 
-using namespace ::indoors::proto;
+static void print_usage()
+{
+  std::cout << "ESRI C++ code assignment, E. Nindl 2021\n\n";
+  std::cout << "Usage:\n";
+  std::cout << "   executable <input-file[s]> <json-ouput-file>\n";
+}
+
+
+std::tuple<double, double, double, double>
+total_spatial_extent(std::vector<Magnetics> const& magnetics_recs) {
+  double x_min = std::numeric_limits<double>::max();
+  double y_min = std::numeric_limits<double>::max();
+  double x_max = std::numeric_limits<double>::min();
+  double y_max = std::numeric_limits<double>::min();
+  for (auto const& magnetics : magnetics_recs) {
+    auto const [x_min_i, y_min_i, x_max_i, y_max_i] = ::calc::spatial_extent(magnetics);
+    x_min = std::min(x_min, x_min_i);
+    y_min = std::min(y_min, y_min_i);
+    x_max = std::max(x_max, x_max_i);
+    y_max = std::max(y_max, y_max_i);
+  }
+  return std::make_tuple(x_min, y_min, x_max, y_max);
+}
+
+
+static bool write_output(std::string const& output_file, SpatialGrid<double>& grid)
+{
+  JsonOutput json_output(output_file.c_str());
+  json_output.add("start_x", grid.start_x());
+  json_output.add("start_y", grid.start_y());
+  json_output.add("spacing", grid.spacing);
+  json_output.add("data", grid.data());
+  return json_output.write();
+}
+
 
 int main(int argc, char* argv[])
 {
-  // Verify that the version of the library that we linked against is
-  // compatible with the version of the headers we compiled against.
-  GOOGLE_PROTOBUF_VERIFY_VERSION;
-
-  std::cout << "ESRI C++ code assignment\n";
-
-  Recording recording;
-  Position positions;
-
-  std::fstream input(argv[1], std::ios::in | std::ios::binary);
-  if (!recording.ParseFromIstream(&input)) {
-    std::cerr << "Failed to parse input file.\n";
-    return -1;
+  if (argc < 3) {
+    print_usage();
+    return 1;
   }
-  std::cout.precision(17);
-  for (int i=0; i < recording.magnetics_size(); i++) {
-    auto const& s = recording.magnetics(i);
-    std::cout << s.t() << ": [" << s.x() << ", " << s.y() << ", " << s.z() << "]\n";
-  }
-  for (int i=0; i < recording.positions_size(); i++) {
-    auto const& s = recording.positions(i);
-    std::cout << s.t() << ": [" << s.x() << ", " << s.y() << "]\n";
+  std::string const output_file{argv[argc - 1]};
+  std::vector<std::string> input_files;
+  for (uint32_t i = 1; i < (argc - 1); i++) {
+    input_files.push_back(argv[i]);
   }
 
-  // Optional:  Delete all global objects allocated by libprotobuf.
-  google::protobuf::ShutdownProtobufLibrary();
+  std::vector<Magnetics> magnetics_recs;
+  std::vector<Positions> groundtruth_recs;
+
+  try {
+    for (auto const& input_file : input_files) {
+      ProtoLoader loader(input_file.c_str());
+      magnetics_recs.push_back(loader.magnetics());
+      groundtruth_recs.push_back(loader.groundtruth());
+    }
+  } catch (std::exception& e) {
+    std::cerr << "Error loading input: " << e.what() << "\n";
+    return 1;
+  }
+
+  for (size_t rec_id = 0; rec_id < magnetics_recs.size(); rec_id++) {
+    Magnetics& magnetics = magnetics_recs[rec_id];
+    Positions& groundtruth = groundtruth_recs[rec_id];
+    ::calc::crop_temporal_inersection(magnetics, groundtruth);
+    if (magnetics.size() == 0) {
+      std::cerr << "Error in groundtruth data\n";
+      return 1;
+    }
+    ::calc::interpolate_positions(magnetics, groundtruth);
+  }
+
+  auto const [x_min, y_min, x_max, y_max] = total_spatial_extent(magnetics_recs);
+  SpatialGrid<std::vector<double>> grid(x_min, y_min, x_max, y_max);
+
+  for (size_t rec_id = 0; rec_id < magnetics_recs.size(); rec_id++) {
+    Magnetics& magnetics = magnetics_recs[rec_id];
+    Positions& groundtruth = groundtruth_recs[rec_id];
+    for (auto& mag : magnetics) {
+      auto& cell = grid.at(mag.position);
+      double const magnitude = ::calc::norm(mag.field.cbegin(), mag.field.cend());
+      cell.push_back(magnitude);
+    }
+  }
+
+  SpatialGrid<double> average_grid(x_min, y_min, x_max, y_max);
+  calc::average_grid(grid, average_grid);
+  if (!write_output(output_file, average_grid)) {
+    std::cout << "Error writing output file: " << output_file << "\n";
+    return 1;
+  }
 
   return 0;
 }
-

src/proto_loader.cpp

@@ -0,0 +1,61 @@
+#include "proto_loader.hpp"
+#include "protocol_buffers_definitions/recordings.pb.h"
+
+#include <fstream>
+#include <stdexcept>
+
+
+
+ProtoLoader::ProtoLoader(char const* f) :
+  filePath_(f)
+{
+  // Verify that the version of the library that we linked against is
+  // compatible with the version of the headers we compiled against.
+  GOOGLE_PROTOBUF_VERIFY_VERSION;
+
+  std::fstream input(filePath_, std::ios::in | std::ios::binary);
+  if (!recording_.ParseFromIstream(&input)) {
+    throw std::runtime_error("Failed to parse input file");
+  }
+}
+
+
+ProtoLoader::~ProtoLoader()
+{
+  // Optional:  Delete all global objects allocated by libprotobuf.
+  ::google::protobuf::ShutdownProtobufLibrary();
+}
+
+
+std::vector<Magnetic> ProtoLoader::magnetics() const
+{
+  double t_prev = 0;
+  std::vector<Magnetic> magnetics;
+  for (int i = 0; i < recording_.magnetics_size(); i++) {
+    auto const& s = recording_.magnetics(i);
+    double const t = s.t();
+    if (t_prev > t) {
+      throw std::runtime_error("Magnetics data not sorted by time");
+    }
+    magnetics.emplace_back(t, s.x(), s.y(), s.z());
+    t_prev = t;
+  }
+  return magnetics;
+}
+
+
+std::vector<Position> ProtoLoader::groundtruth() const
+{
+  double t_prev = 0;
+  std::vector<Position> groundtruth;
+  for (int i=0; i < recording_.positions_size(); i++) {
+    auto const& s = recording_.positions(i);
+    double const t = s.t();
+    if ((t - t_prev) < dt_min) {
+      throw std::runtime_error("Groundtruth data invalid");
+    }
+    groundtruth.emplace_back(t, s.x(), s.y());
+    t_prev = t;
+  }
+  return groundtruth;
+}

src/proto_loader.hpp

@@ -0,0 +1,24 @@
+#ifndef PROTOLOADER_HPP_
+#define PROTOLOADER_HPP_
+
+#include "data.hpp"
+#include "protocol_buffers_definitions/recordings.pb.h"
+#include <vector>
+
+
+class ProtoLoader {
+public:
+  explicit ProtoLoader(char const* file_path);
+  ~ProtoLoader();
+
+  std::vector<Magnetic> magnetics() const;
+  std::vector<Position> groundtruth() const;
+
+  static constexpr double dt_min{1e-3};
+
+private:
+  char const* filePath_;
+  ::indoors::proto::Recording recording_;
+};
+
+#endif /* PROTOLOADER_HPP_ */

src/spatial_grid.hpp

@@ -0,0 +1,69 @@
+#ifndef SPATIALGRID_HPP_
+#define SPATIALGRID_HPP_
+
+#include <array>
+#include <cmath>
+#include <cstdint>
+#include <vector>
+
+
+template<typename value_t>
+class SpatialGrid {
+public:
+  SpatialGrid() = delete;
+  explicit SpatialGrid(double x_start, double y_start, double x_end, double y_end) :
+    offset_({static_cast<size_t>(x_start / spacing), static_cast<size_t>(y_start / spacing)}),
+    size_x_(static_cast<size_t>(std::ceil(x_end / spacing)) - offset_[0]),
+    size_y_(static_cast<size_t>(std::ceil(y_end / spacing)) - offset_[1]),
+    grid_(size_x_, std::vector<value_t>(size_y_))
+  {}
+  ~SpatialGrid() = default;
+
+  value_t& at(double x, double y)
+  {
+    size_t const id_x{static_cast<size_t>(x / spacing) - offset_[0]};
+    size_t const id_y{static_cast<size_t>(y / spacing) - offset_[1]};
+    return grid_[id_x][id_y];
+  }
+  value_t& at(std::array<double, 2> pos)
+  {
+    return at(pos[0], pos[1]);
+  }
+
+  std::vector<value_t>& operator[](size_t idx)
+  {
+    return grid_[idx];
+  }
+  size_t size_x() const
+  {
+    return grid_.size();
+  }
+  size_t size_y() const
+  {
+    return grid_[0].size();
+  }
+  size_t start_x() const noexcept
+  {
+    return offset_[0] * spacing;
+  }
+  size_t start_y() const noexcept
+  {
+    return offset_[1] * spacing;
+  }
+
+  std::vector<std::vector<value_t>>& data() {
+    return grid_;
+  }
+
+  static constexpr size_t spacing{5};
+
+private:
+  size_t const offset_[2];
+  size_t const size_x_;
+  size_t const size_y_;
+
+  std::vector<std::vector<value_t>> grid_;
+};
+
+
+#endif /* SPATIALGRID_HPP_ */