H5CPP - Canada Dry

 1: temperature = np.random.random(1024)
 2: wind = np.random.random(2048)
 3: f = h5py.File('weather.hdf5')
 4: f["/15/temperature"] = temperature
 5: f["/15/temperature"].attrs["dt"] = 10.0
 6: f["/15/wind"] = wind
 7: 
 8: dataset[0:10:2]
 9: 
10: big_dataset = f.create_dataset("big",
11:                                shape=(1024, 1024, 1024, 512),
12:                                dtype='float32')
13: big_dataset[344, 678, 23, 36] = 42.0
14: 
15: compressed_dataset = f.create_dataset("comp", shape=(1024,),
16:                                       dtype='int32',
17:                                       compression='gzip')

 1: fvec temperature = arma::randu<fvec>(1024);
 2: fvec wind = arma::randu<fvec>(2048);
 3: auto fd = h5::create("weather.hdf5", H5F_ACC_TRUNC);
 4: auto ds = h5::write(fd, "/15/temperature", temperature);
 5: ds["dt"] = 10.0f;
 6: h5::write(fd, "/15/wind", wind);
 7: 
 8: h5::read<fvec>(ds, h5::offset{0}, h5::count{5}, h5::stride{2});
 9: 
10: auto big = h5::create<float>(fd,"big"
11:                              ,h5::current_dims{1024, 1024, 1024, 512}
12:                              ,h5::chunk{16, 16, 16, 8});
13: float value {42.0};
14: h5::write<float>(ds, &value
15:                  ,h5::offset{344, 678, 23, 36}
16:                  ,h5::count{1, 1, 1, 1});
17: 
18: auto comp = h5::create<int>(fd, "comp"
19:                             ,h5::current_dims{1024}
20:                             ,h5::chunk{64} | h5::gzip{4});

fd = H5Fcreate("weather.hdf5", H5F_ACC_TRUNC,
               H5P_DEFAULT, H5P_DEFAULT);

// > 20 different API calls:
//
// H5Acreate, H5Aclose, H5Awrite,
// H5Dcreate, H5Dclose, H5Dread, H5Dwrite,
// H5Pcreate, H5Pclose, H5Pset_create_intermediate_group,
// H5Pset_layout, H5Pset_chunk, H5Pset_deflate,
// H5Screate, H5Sclose, H5Screate_simple, H5Sselect_hyperslab

H5Fclose(fd);

 1: // H5CPP_CONVERSION_EXPLICIT
 2: // H5CPP_CONVERSION_FROM_CAPI_DISABLED
 3: // H5CPP_CONVERSION_TO_CAPI_DISABLED
 4: 
 5: h5::fd_t fd = h5::create("example.h5",H5F_ACC_TRUNC);
 6: hsize_t size {0};
 7: 
 8: // compiler error if H5CPP_CONVERSION_EXPLICIT is defined
 9: H5Fget_filesize(fd, &size);
10: 
11: // compiler error if H5CPP_CONVERSION_TO_CAPI_DISABLED is def.
12: H5Fget_filesize(static_cast<hid_t>(fd), &size);

 1: // capture errors centrally with the granularity you desire
 2: try {
 3:     my_deeply_embedded_io_calls();
 4: } catch ( const h5::error::io::dataset::create& e ){
 5:     // handle file creation error
 6: } catch ( const h5::error::io::dataset::write& e ){
 7: } catch ( const h5::error::io::file::create& e ){
 8: } catch ( const h5::error::io::file::close& e ){
 9: } catch ( const h5::any& e ) {
10:     std::cerr << e.what() << std::endl;
11: }

 1: typedef struct s1_t {  // Write this
 2:   int a; float b; double c;
 3: } s1_t;
 4: typedef struct s2_t {  // Read that
 5:   double c; int a;
 6: } s2_t;
 7: 
 8: // Easy
 9: 
10: std::vector<s1_t> s1(LENGTH);
11: std::generate( std::begin(s1), std::end(s1), [i=-1]() mutable {
12:   return s1_t{++i,static_cast<float>(i*i), 1.0/(i+1)}; });
13: 
14: auto fd = h5::create(H5FILE_NAME, H5F_ACC_TRUNC);
15: h5::write(fd, DATASETNAME, s1);
16: 
17: auto data = h5::read< std::vector<s2_t> >(fd, DATASETNAME);
18: std::cout << "reading back data previously written:\n\t";
19: for (auto r:data)
20:   std::cout << r.c << " ";
21: std::cout << std::endl;

 1: #include <h5cpp/core>
 2: #include "your_data_definition.h"  // <- struct { ... };
 3: #include <h5cpp/io>
 4: auto fd = h5::create("NYSE high freq dataset.h5");
 5: h5::pt_t pt = h5::create<ns::nyse_stock_quote>
 6:   (fd
 7:    ,"price_quotes/2019-01-24.qte"
 8:    ,h5::max_dims{H5S_UNLIMITED}
 9:    ,h5::chunk{1024} | h5::gzip{9} );
10: quote_update_t qu;
11: bool having_a_good_day{true};
12: while( having_a_good_day ){
13:     try{
14:         recieve_data_from_udp_stream( qu )
15:         h5::append(pt, qu);
16:     } catch ( ... ){
17:       if( cant_fix_connection() )
18:             having_a_good_day = false;
19:     }
20: }

1: h5::ds_t ds = h5::open(fd,"some_dataset", h5::high_throughput);