Module org.hdfgroup.object
Package hdf.object.h5

Class H5CompoundAttr

Object
hdf.object.HObject
hdf.object.Dataset
hdf.object.CompoundDS
hdf.object.h5.H5CompoundAttr
All Implemented Interfaces:
Attribute, CompoundDataFormat, DataFormat, H5Attribute, Serializable
public class H5CompoundAttr extends CompoundDS implements H5Attribute
The H5CompoundAttr class defines an HDF5 attribute of compound datatypes. An attribute is a (name, value) pair of metadata attached to a primary data object such as a dataset, group or named datatype. Like a dataset, an attribute has a name, datatype and dataspace. A HDF5 compound datatype is similar to a struct in C or a common block in Fortran: it is a collection of one or more atomic types or small arrays of such types. Each member of a compound type has a name which is unique within that type, and a byte offset that determines the first byte (smallest byte address) of that member in a compound datum. For more information on HDF5 attributes and datatypes, read the HDF5 Attributes in HDF5 User Guide There are two basic types of compound attributes: simple compound data and nested compound data. Members of a simple compound attribute have atomic datatypes. Members of a nested compound attribute are compound or array of compound data. Since Java does not understand C structures, we cannot directly read/write compound data values as in the following C example. 
 typedef struct s1_t {
         int    a;
         float  b;
         double c;
         } s1_t;
     s1_t       s1[LENGTH];
     ...
     H5Dwrite(..., s1);
     H5Dread(..., s1);
Values of compound data fields are stored in java.util.Vector object. We read and write compound data by fields instead of compound structure. As for the example above, the java.util.Vector object has three elements: int[LENGTH], float[LENGTH] and double[LENGTH]. Since Java understands the primitive datatypes of int, float and double, we will be able to read/write the compound data by field.
Version:
1.0 6/15/2021
Author:
Allen Byrne
See Also: