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HDF5 Tutorial: Advanced Topics
Selecting Individual Points

Description

This topic shows how to select and write to independent points in a dataset.

Programming Example

Description

The H5Sselect_elements / h5sselect_elements_f call allows you to select individual points in a dataspace. By use of it, you can read and write to individual points in a dataset.

C example

h5_copy.c

FORTRAN example

selectele.f90

Python example

h5_copy.py

For details on compiling an HDF5 application click here.

Remarks

H5Sselect_elements / h5sselect_elements_f selects array elements to be included in the selection for a dataspace.
The coord array is a two-dimensional array of size NUMP x RANK in C (RANK x NUMP in FORTRAN) where NUMP is the number of selected points and RANK is the rank of the dataset.

Note that these coordinates are 0-based in C and 1-based in FORTRAN.
Consider the non-zero elements of the following array:
```
            0  59   0  53
            0   0   0   0
            0   0   1   0    
```
In C, the coord array selecting these points would be as follows:
```
            0   1
            0   3
            2   2            
```
While in FORTRAN, the coord array would be as follows:
```
            1   1   3
            2   4   3      
  
```

The example code calls H5Scopy / h5scopy_f to create an exact copy of a dataspace.

File Contents

Following is the DDL for copy1.h5 and copy2.h5, as viewed with the following commands:
h5dump copy1.h5
h5dump copy2.h5

Fig. S.1a copy1.h5 in DDL

   HDF5 "copy1.h5" {
   GROUP "/" {
      DATASET "Copy1" {
         DATATYPE { H5T_STD_I32BE }
         DATASPACE { SIMPLE ( 3, 4 ) / ( 3, 4 ) }
         DATA {
            0, 59, 0, 53,
            0, 0, 0, 0,
            0, 0, 0, 0
         }
      }
   }
   }

Fig. S.1b copy2.h5 in DDL

   HDF5 "copy2.h5" {
   GROUP "/" {
      DATASET "Copy2" {
         DATATYPE { H5T_STD_I32BE }
         DATASPACE { SIMPLE ( 3, 4 ) / ( 3, 4 ) }
         DATA {
            1, 59, 1, 53,
            1, 1, 1, 1,
            1, 1, 1, 1
         }
      }
   }
   }

FORTRAN:

Fig. S.2a copy1.h5 in DDL

   HDF5 "copy1.h5" {
   GROUP "/" {
      DATASET "Copy1" {
         DATATYPE { H5T_STD_I32BE }
         DATASPACE { SIMPLE ( 4, 3 ) / ( 4, 3 ) }
         DATA {
            0, 0, 0,
            53, 0, 0,
            0, 0, 0,
            59, 0, 0
         }
      }
   }
   }

Fig. S.2b copy2.h5 in DDL

   HDF5 "copy2.h5" {
   GROUP "/" {
      DATASET "Copy2" {
         DATATYPE { H5T_STD_I32BE }
         DATASPACE { SIMPLE ( 4, 3 ) / ( 4, 3 ) }
         DATA {
            1, 1, 1,
            53, 1, 1,
            1, 1, 1,
            59, 1, 1
         }
      }
   }
   }

- - Last modified: 21 December 2016

HDF5 Tutorial: Advanced Topics Selecting Individual Points

Contents:

Description

Programming Example

Description

Remarks

File Contents

HDF5 Tutorial: Advanced Topics
Selecting Individual Points