csv.md

CSV (Comma Separated Values)

Glaze supports CSV reading and writing for glaze meta objects and standard map types.

By default Glaze writes out structures row-wise, which is more efficient if all the data is available at once. However, column-wise CSV format is also supported.

Glaze meta example:

struct my_struct
{
   std::vector<int> num1{};
   std::deque<float> num2{};
   std::vector<bool> maybe{};
   std::vector<std::array<int, 3>> v3s{};
};

template <>
struct glz::meta<my_struct>
{
   using T = my_struct;
   static constexpr auto value = glz::object("num1", &T::num1, "num2", &T::num2, "maybe", &T::maybe, "v3s", &T::v3s);
};

Reading/Writing column-wise:

std::string input_col =
  R"(num1,num2,maybe,v3s[0],v3s[1],v3s[2]
11,22,1,1,1,1
33,44,1,2,2,2
55,66,0,3,3,3
77,88,0,4,4,4)";

my_struct obj{};

read_csv<colwise>(obj, input_col);

expect(obj.num1[0] == 11);
expect(obj.num2[2] == 66);
expect(obj.maybe[3] == false);
expect(obj.v3s[0] == std::array{1, 1, 1});
expect(obj.v3s[1] == std::array{2, 2, 2});
expect(obj.v3s[2] == std::array{3, 3, 3});
expect(obj.v3s[3] == std::array{4, 4, 4});

std::string out{};

write<opts{.format = csv, .layout = colwise}>(obj, out);
expect(out ==
       R"(num1,num2,maybe,v3s[0],v3s[1],v3s[2]
11,22,1,1,1,1
33,44,1,2,2,2
55,66,0,3,3,3
77,88,0,4,4,4
)");

expect(!write_file_csv<colwise>(obj, "csv_test_colwise.csv"));