105 lines
3.1 KiB
Markdown
105 lines
3.1 KiB
Markdown
+++
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title = "Single-header C++ Matrix Market Reader"
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date = 2021-07-30T00:00:00
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lastmod = 2021-07-30T00:00:00
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draft = false
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# Authors. Comma separated list, e.g. `["Bob Smith", "David Jones"]`.
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authors = ["Carl Pearson"]
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tags = ["sparse"]
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summary = "GPLv3 single-header C++11 Matrix Market Reader"
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# Projects (optional).
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# Associate this post with one or more of your projects.
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# Simply enter your project's folder or file name without extension.
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# E.g. `projects = ["deep-learning"]` references
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# `content/project/deep-learning/index.md`.
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# Otherwise, set `projects = []`.
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projects = []
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# Featured image
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# To use, add an image named `featured.jpg/png` to your project's folder.
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[image]
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# Caption (optional)
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caption = ""
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# Focal point (optional)
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# Options: Smart, Center, TopLeft, Top, TopRight, Left, Right, BottomLeft, Bottom, BottomRight
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focal_point = "Center"
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# Show image only in page previews?
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preview_only = true
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categories = []
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# Set captions for image gallery.
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+++
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I'm continually re-writing some C++ code to read [Matrix Market files](https://math.nist.gov/MatrixMarket/formats.html), a common format for distributing matrices.
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I finally got around to writing something that I should be able to reuse.
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The code is [available on github](github.com/cwpearson/matrix-market).
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An example follows:
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```c++
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#include "mm/mm.hpp"
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int main(int argc, char **argv)
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{
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if (argc < 2)
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{
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std::cerr << "Usage: " << argv[0] << " <file.mtx>\n";
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exit(EXIT_FAILURE);
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}
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const std::string path = argv[1];
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{
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std::cout << "with Ordinal=int, Scalar=float, Offset=size_t" << std::endl;
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typedef int Ordinal;
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typedef float Scalar;
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typedef MtxReader<Ordinal, Scalar> reader_t;
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typedef typename reader_t::coo_type coo_t;
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typedef typename coo_t::entry_type entry_t;
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// read matrix as coo
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reader_t reader(path);
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coo_t coo = reader.read_coo();
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// non-zeros, rows, cols
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std::cout << coo.nnz() << std::endl; // size_t
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std::cout << coo.num_rows() << "," << coo.num_cols() << std::endl; // int
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// first entry
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entry_t e = coo.entries[0];
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std::cout << e.i << "," << e.j << std::endl; // int, int
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std::cout << e.e << std::endl; // float
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}
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{
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std::cout << "with Ordinal=int64_t, Scalar=std::complex<float>, Offset=int" << std::endl;
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typedef MtxReader<int64_t, std::complex<float>, int> reader_t;
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typedef typename reader_t::coo_type coo_t;
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typedef typename coo_t::entry_type entry_t;
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// read matrix as coo
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reader_t reader(path);
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coo_t coo = reader.read_coo();
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// non-zeros, rows, cols
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std::cout << coo.nnz() << std::endl; // int
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std::cout << coo.num_rows() << "," << coo.num_cols() << std::endl; // complex<double>
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// first entry
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entry_t e = coo.entries[0];
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std::cout << e.i << "," << e.j << std::endl; // int64_t
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std::cout << e.e << std::endl; // complex<double>
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}
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return 0;
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}
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``` |