3.1 KiB
3.1 KiB
+++ title = "Single-header C++ Matrix Market Reader" date = 2021-07-30T00:00:00 lastmod = 2021-07-30T00:00:00 draft = false
Authors. Comma separated list, e.g. ["Bob Smith", "David Jones"].
authors = ["Carl Pearson"]
tags = ["sparse"]
summary = "GPLv3 single-header C++11 Matrix Market Reader"
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+++
I'm continually re-writing some C++ code to read Matrix Market files, a common format for distributing matrices. I finally got around to writing something that I should be able to reuse.
The code is available on github.
An example follows:
#include "mm/mm.hpp"
int main(int argc, char **argv)
{
if (argc < 2)
{
std::cerr << "Usage: " << argv[0] << " <file.mtx>\n";
exit(EXIT_FAILURE);
}
const std::string path = argv[1];
{
std::cout << "with Ordinal=int, Scalar=float, Offset=size_t" << std::endl;
typedef int Ordinal;
typedef float Scalar;
typedef MtxReader<Ordinal, Scalar> reader_t;
typedef typename reader_t::coo_type coo_t;
typedef typename coo_t::entry_type entry_t;
// read matrix as coo
reader_t reader(path);
coo_t coo = reader.read_coo();
// non-zeros, rows, cols
std::cout << coo.nnz() << std::endl; // size_t
std::cout << coo.num_rows() << "," << coo.num_cols() << std::endl; // int
// first entry
entry_t e = coo.entries[0];
std::cout << e.i << "," << e.j << std::endl; // int, int
std::cout << e.e << std::endl; // float
}
{
std::cout << "with Ordinal=int64_t, Scalar=std::complex<float>, Offset=int" << std::endl;
typedef MtxReader<int64_t, std::complex<float>, int> reader_t;
typedef typename reader_t::coo_type coo_t;
typedef typename coo_t::entry_type entry_t;
// read matrix as coo
reader_t reader(path);
coo_t coo = reader.read_coo();
// non-zeros, rows, cols
std::cout << coo.nnz() << std::endl; // int
std::cout << coo.num_rows() << "," << coo.num_cols() << std::endl; // complex<double>
// first entry
entry_t e = coo.entries[0];
std::cout << e.i << "," << e.j << std::endl; // int64_t
std::cout << e.e << std::endl; // complex<double>
}
return 0;
}