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Diffstat (limited to 'c++/examples/writedata.cpp')
| -rw-r--r-- | c++/examples/writedata.cpp | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/c++/examples/writedata.cpp b/c++/examples/writedata.cpp new file mode 100644 index 0000000..8179113 --- /dev/null +++ b/c++/examples/writedata.cpp @@ -0,0 +1,227 @@ +/* + * This program shows how the select_hyperslab and select_elements + * functions are used to write selected data from memory to the file. + * Program takes 48 elements from the linear buffer and writes them into + * the matrix using 3x2 blocks, (4,3) stride and (2,4) count. + * Then four elements of the matrix are overwritten with the new values and + * file is closed. Program reopens the file and reads and displays the result. + */ + +#include <string> +#ifndef H5_NO_NAMESPACE +using namespace std; +#endif + +#ifdef OLD_HEADER_FILENAME +#include <iostream.h> +#else +#include <iostream> +#endif +#include "H5Cpp.h" + +#ifndef H5_NO_NAMESPACE +using namespace H5; +#endif + +const string FILE_NAME( "Select.h5" ); +const string DATASET_NAME( "Matrix in file" ); +const int MSPACE1_RANK = 1; // Rank of the first dataset in memory +const int MSPACE1_DIM = 50; // Dataset size in memory +const int MSPACE2_RANK = 1; // Rank of the second dataset in memory +const int MSPACE2_DIM = 4; // Dataset size in memory +const int FSPACE_RANK = 2; // Dataset rank as it is stored in the file +const int FSPACE_DIM1 = 8; // Dimension sizes of the dataset as it is... +const int FSPACE_DIM2 = 12; // ...stored in the file +const int MSPACE_DIM1 = 8; // We will read dataset back from the file... +const int MSPACE_DIM2 = 12; // ...to the dataset in memory with these ... + // ...dataspace parameters +const int NPOINTS = 4; // Number of points that will be selected... + // ...and overwritten + +int main (void) +{ + /* + * Buffers' initialization. + */ + uint i,j; + int vector[MSPACE1_DIM]; + vector[0] = vector[MSPACE1_DIM - 1] = -1; + for (i = 1; i < MSPACE1_DIM - 1; i++) + vector[i] = i; + + int matrix[MSPACE_DIM1][MSPACE_DIM2]; + for (i = 0; i < MSPACE_DIM1; i++) + { + for (j = 0; j < MSPACE_DIM2; j++) + matrix[i][j] = 0; + } + + // Try block to detect exceptions raised by any of the calls inside it + try + { + // + //Create a file. + // + H5File* file = new H5File( FILE_NAME, H5F_ACC_TRUNC ); + + // + //Create dataspace for the dataset in the file. + // + hsize_t fdim[] = {FSPACE_DIM1, FSPACE_DIM2}; // dim sizes of ds (on disk) + DataSpace fspace( FSPACE_RANK, fdim ); + + // + // Create dataset and write it into the file. + // + DataSet* dataset = new DataSet( + file->createDataSet( DATASET_NAME, PredType::NATIVE_INT, fspace )); + dataset->write( matrix, PredType::NATIVE_INT ); + + // + // Select hyperslab for the dataset in the file, using 3x2 blocks, + // (4,3) stride and (2,4) count starting at the position (0,1). + // + hssize_t start[2]; // Start of hyperslab + hsize_t stride[2]; // Stride of hyperslab + hsize_t count[2]; // Block count + hsize_t block[2]; // Block sizes + start[0] = 0; start[1] = 1; + stride[0] = 4; stride[1] = 3; + count[0] = 2; count[1] = 4; + block[0] = 3; block[1] = 2; + fspace.selectHyperslab( H5S_SELECT_SET, count, start, stride, block); + + // + // Create dataspace for the first dataset. + // + hsize_t dim1[] = {MSPACE1_DIM}; /* Dimension size of the first dataset + (in memory) */ + DataSpace mspace1( MSPACE1_RANK, dim1 ); + + /* + * Select hyperslab. + * We will use 48 elements of the vector buffer starting at the + * second element. Selected elements are 1 2 3 . . . 48 + */ + start[0] = 1; + stride[0] = 1; + count[0] = 48; + block[0] = 1; + mspace1.selectHyperslab( H5S_SELECT_SET, count, start, stride, block); + + /* + * Write selection from the vector buffer to the dataset in the file. + * + * File dataset should look like this: + * 0 1 2 0 3 4 0 5 6 0 7 8 + * 0 9 10 0 11 12 0 13 14 0 15 16 + * 0 17 18 0 19 20 0 21 22 0 23 24 + * 0 0 0 0 0 0 0 0 0 0 0 0 + * 0 25 26 0 27 28 0 29 30 0 31 32 + * 0 33 34 0 35 36 0 37 38 0 39 40 + * 0 41 42 0 43 44 0 45 46 0 47 48 + * 0 0 0 0 0 0 0 0 0 0 0 0 + */ + dataset->write( vector, PredType::NATIVE_INT, mspace1, fspace ); + + /* + * Reset the selection for the file dataspace fid. + */ + fspace.selectNone(); + + /* + * Create dataspace for the second dataset. + */ + hsize_t dim2[] = {MSPACE2_DIM}; /* Dimension size of the second dataset + (in memory */ + DataSpace mspace2( MSPACE2_RANK, dim2 ); + + /* + * Select sequence of NPOINTS points in the file dataspace. + */ + hssize_t coord[NPOINTS][FSPACE_RANK]; /* Array to store selected points + from the file dataspace */ + coord[0][0] = 0; coord[0][1] = 0; + coord[1][0] = 3; coord[1][1] = 3; + coord[2][0] = 3; coord[2][1] = 5; + coord[3][0] = 5; coord[3][1] = 6; + + fspace.selectElements( H5S_SELECT_SET, NPOINTS, (const hssize_t **)coord); + + /* + * Write new selection of points to the dataset. + */ + int values[] = {53, 59, 61, 67}; /* New values to be written */ + dataset->write( values, PredType::NATIVE_INT, mspace2, fspace ); + + /* + * File dataset should look like this: + * 53 1 2 0 3 4 0 5 6 0 7 8 + * 0 9 10 0 11 12 0 13 14 0 15 16 + * 0 17 18 0 19 20 0 21 22 0 23 24 + * 0 0 0 59 0 61 0 0 0 0 0 0 + * 0 25 26 0 27 28 0 29 30 0 31 32 + * 0 33 34 0 35 36 67 37 38 0 39 40 + * 0 41 42 0 43 44 0 45 46 0 47 48 + * 0 0 0 0 0 0 0 0 0 0 0 0 + * + */ + + /* + * Close the dataset and the file. + */ + delete dataset; + delete file; + + /* + * Open the file. + */ + file = new H5File( FILE_NAME, H5F_ACC_RDONLY ); + + /* + * Open the dataset. + */ + dataset = new DataSet( file->openDataSet( DATASET_NAME )); + + /* + * Read data back to the buffer matrix. + */ + dataset->read( matrix, PredType::NATIVE_INT ); + + /* + * Display the result. + */ + for (i=0; i < MSPACE_DIM1; i++) + { + for(j=0; j < MSPACE_DIM2; j++) + cout << matrix[i][j] << " "; + cout << endl; + } + + /* + * Close the dataset and the file. + */ + delete dataset; + delete file; + } // end of try block + + // catch failure caused by the H5File operations + catch( FileIException error ) + { + error.printError(); + } + + // catch failure caused by the DataSet operations + catch( DataSetIException error ) + { + error.printError(); + } + + // catch failure caused by the DataSpace operations + catch( DataSpaceIException error ) + { + error.printError(); + } + + return 0; +} |