1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
2 * Copyright by The HDF Group. *
3 * Copyright by the Board of Trustees of the University of Illinois. *
4 * All rights reserved. *
5 * *
6 * This file is part of HDF5. The full HDF5 copyright notice, including *
7 * terms governing use, modification, and redistribution, is contained in *
8 * the COPYING file, which can be found at the root of the source code *
9 * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases. *
10 * If you do not have access to either file, you may request a copy from *
11 * help@hdfgroup.org. *
12 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
13
14 /*
15 * This example illustrates how to create a compressed dataset.
16 * It is used in the HDF5 Tutorial.
17 */
18
19 #include <iostream>
20 using std::cout;
21 using std::endl;
22
23 #include <string>
24 #include "H5Cpp.h"
25 using namespace H5;
26
27 const H5std_string FILE_NAME("h5tutr_cmprss.h5");
28 const H5std_string DATASET_NAME("Compressed_Data");
29 const int DIM0 = 100;
30 const int DIM1 = 20;
31
main(void)32 int main (void)
33 {
34 hsize_t dims[2] = { DIM0, DIM1 }; // dataset dimensions
35 hsize_t chunk_dims[2] = { 20, 20 }; // chunk dimensions
36 int i,j, buf[DIM0][DIM1];
37
38 // Try block to detect exceptions raised by any of the calls inside it
39 try
40 {
41 // Turn off the auto-printing when failure occurs so that we can
42 // handle the errors appropriately
43 Exception::dontPrint();
44
45 // Create a new file using the default property lists.
46 H5File file(FILE_NAME, H5F_ACC_TRUNC);
47
48 // Create the data space for the dataset.
49 DataSpace *dataspace = new DataSpace(2, dims);
50
51 // Modify dataset creation property to enable chunking
52 DSetCreatPropList *plist = new DSetCreatPropList;
53 plist->setChunk(2, chunk_dims);
54
55 // Set ZLIB (DEFLATE) Compression using level 6.
56 // To use SZIP compression comment out this line.
57 plist->setDeflate(6);
58
59 // Uncomment these lines to set SZIP Compression
60 // unsigned szip_options_mask = H5_SZIP_NN_OPTION_MASK;
61 // unsigned szip_pixels_per_block = 16;
62 // plist->setSzip(szip_options_mask, szip_pixels_per_block);
63
64 // Create the dataset.
65 DataSet *dataset = new DataSet(file.createDataSet( DATASET_NAME,
66 PredType::STD_I32BE, *dataspace, *plist) );
67
68 for (i = 0; i< DIM0; i++)
69 for (j=0; j<DIM1; j++)
70 buf[i][j] = i+j;
71
72 // Write data to dataset.
73 dataset->write(buf, PredType::NATIVE_INT);
74
75 // Close objects and file. Either approach will close the HDF5 item.
76 delete dataspace;
77 delete dataset;
78 delete plist;
79 file.close();
80
81 // -----------------------------------------------
82 // Re-open the file and dataset, retrieve filter
83 // information for dataset and read the data back.
84 // -----------------------------------------------
85
86 int rbuf[DIM0][DIM1];
87 int numfilt;
88 size_t nelmts={1}, namelen={1};
89 unsigned flags, filter_info, cd_values[1], idx;
90 char name[1];
91 H5Z_filter_t filter_type;
92
93 // Open the file and the dataset in the file.
94 file.openFile(FILE_NAME, H5F_ACC_RDONLY);
95 dataset = new DataSet(file.openDataSet( DATASET_NAME));
96
97 // Get the create property list of the dataset.
98 plist = new DSetCreatPropList(dataset->getCreatePlist ());
99
100 // Get the number of filters associated with the dataset.
101 numfilt = plist->getNfilters();
102 cout << "Number of filters associated with dataset: " << numfilt << endl;
103
104 for (idx=0; idx < numfilt; idx++) {
105 nelmts = 0;
106
107 filter_type = plist->getFilter(idx, flags, nelmts, cd_values, namelen, name , filter_info);
108
109 cout << "Filter Type: ";
110
111 switch (filter_type) {
112 case H5Z_FILTER_DEFLATE:
113 cout << "H5Z_FILTER_DEFLATE" << endl;
114 break;
115 case H5Z_FILTER_SZIP:
116 cout << "H5Z_FILTER_SZIP" << endl;
117 break;
118 default:
119 cout << "Other filter type included." << endl;
120 }
121 }
122
123 // Read data.
124 dataset->read(rbuf, PredType::NATIVE_INT);
125
126 delete plist;
127 delete dataset;
128 file.close(); // can be skipped
129
130 } // end of try block
131
132 // catch failure caused by the H5File operations
133 catch(FileIException error)
134 {
135 error.printErrorStack();
136 return -1;
137 }
138
139 // catch failure caused by the DataSet operations
140 catch(DataSetIException error)
141 {
142 error.printErrorStack();
143 return -1;
144 }
145
146 // catch failure caused by the DataSpace operations
147 catch(DataSpaceIException error)
148 {
149 error.printErrorStack();
150 return -1;
151 }
152
153 return 0; // successfully terminated
154 }
155
156