1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
|
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the files COPYING and Copyright.html. COPYING can be found at the root *
* of the source code distribution tree; Copyright.html can be found at the *
* root level of an installed copy of the electronic HDF5 document set and *
* is linked from the top-level documents page. It can also be found at *
* http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html. If you do not have *
* access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example shows how to read data from a chunked dataset.
* We will read from the file created by h5_extend_write.c
*/
#include "hdf5.h"
#define H5FILE_NAME "SDSextendible.h5"
#define DATASETNAME "ExtendibleArray"
#define RANK 2
#define RANKC 1
#define NX 10
#define NY 5
int
main (void)
{
hid_t file; /* handles */
hid_t dataset;
hid_t filespace;
hid_t memspace;
hid_t cparms;
hsize_t dims[2]; /* dataset and chunk dimensions*/
hsize_t chunk_dims[2];
hsize_t col_dims[1];
hsize_t count[2];
hsize_t offset[2];
herr_t status, status_n;
int data_out[NX][NY]; /* buffer for dataset to be read */
int chunk_out[2][5]; /* buffer for chunk to be read */
int column[10]; /* buffer for column to be read */
int rank, rank_chunk;
hsize_t i, j;
/*
* Open the file and the dataset.
*/
file = H5Fopen(H5FILE_NAME, H5F_ACC_RDONLY, H5P_DEFAULT);
dataset = H5Dopen(file, DATASETNAME);
/*
* Get dataset rank and dimension.
*/
filespace = H5Dget_space(dataset); /* Get filespace handle first. */
rank = H5Sget_simple_extent_ndims(filespace);
status_n = H5Sget_simple_extent_dims(filespace, dims, NULL);
printf("dataset rank %d, dimensions %lu x %lu\n",
rank, (unsigned long)(dims[0]), (unsigned long)(dims[1]));
/*
* Define the memory space to read dataset.
*/
memspace = H5Screate_simple(RANK,dims,NULL);
/*
* Read dataset back and display.
*/
status = H5Dread(dataset, H5T_NATIVE_INT, memspace, filespace,
H5P_DEFAULT, data_out);
printf("\n");
printf("Dataset: \n");
for (j = 0; j < dims[0]; j++) {
for (i = 0; i < dims[1]; i++) printf("%d ", data_out[j][i]);
printf("\n");
}
/*
* Close/release resources.
*/
H5Sclose(memspace);
/*
* dataset rank 2, dimensions 10 x 5
* chunk rank 2, dimensions 2 x 5
* Dataset:
* 1 1 1 3 3
* 1 1 1 3 3
* 1 1 1 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
*/
/*
* Read the third column from the dataset.
* First define memory dataspace, then define hyperslab
* and read it into column array.
*/
col_dims[0] = 10;
memspace = H5Screate_simple(RANKC, col_dims, NULL);
/*
* Define the column (hyperslab) to read.
*/
offset[0] = 0;
offset[1] = 2;
count[0] = 10;
count[1] = 1;
status = H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL,
count, NULL);
status = H5Dread(dataset, H5T_NATIVE_INT, memspace, filespace,
H5P_DEFAULT, column);
printf("\n");
printf("Third column: \n");
for (i = 0; i < 10; i++) {
printf("%d \n", column[i]);
}
/*
* Close/release resources.
*/
H5Sclose(memspace);
/*
* Third column:
* 1
* 1
* 1
* 0
* 0
* 0
* 0
* 0
* 0
* 0
*/
/*
* Get creation properties list.
*/
cparms = H5Dget_create_plist(dataset); /* Get properties handle first. */
if (H5D_CHUNKED == H5Pget_layout(cparms)) {
/*
* Get chunking information: rank and dimensions
*/
rank_chunk = H5Pget_chunk(cparms, 2, chunk_dims);
printf("chunk rank %d, dimensions %lu x %lu\n", rank_chunk,
(unsigned long)(chunk_dims[0]), (unsigned long)(chunk_dims[1]));
/*
* Define the memory space to read a chunk.
*/
memspace = H5Screate_simple(rank_chunk,chunk_dims,NULL);
/*
* Define chunk in the file (hyperslab) to read.
*/
offset[0] = 2;
offset[1] = 0;
count[0] = chunk_dims[0];
count[1] = chunk_dims[1];
status = H5Sselect_hyperslab(filespace, H5S_SELECT_SET, offset, NULL,
count, NULL);
/*
* Read chunk back and display.
*/
status = H5Dread(dataset, H5T_NATIVE_INT, memspace, filespace,
H5P_DEFAULT, chunk_out);
printf("\n");
printf("Chunk: \n");
for (j = 0; j < chunk_dims[0]; j++) {
for (i = 0; i < chunk_dims[1]; i++) printf("%d ", chunk_out[j][i]);
printf("\n");
}
/*
* Chunk:
* 1 1 1 0 0
* 2 0 0 0 0
*/
/*
* Close/release resources.
*/
H5Sclose(memspace);
}
/*
* Close/release resources.
*/
H5Pclose(cparms);
H5Dclose(dataset);
H5Sclose(filespace);
H5Fclose(file);
return 0;
}
|
