h5writeAttribute

Purpose

Writes a GAUSS matrix, N-dimensional array or string array as an attribute of an HDF5 dataset.

Format

retcode = h5writeAttribute(fname, dname, attr_name, attr)
Parameters:
  • fname (string) – a name of the HDF5 file.
  • dname (string) – a name of the dataset in the HDF5 file.
  • attr_name (string) – the name of attribute to write.
  • attr (matrix) – N-dimensional array or string array, the contents of the attribute.
Returns:

retcode (scalar) – 0 if successful, non-zero otherwise.


  • Attributes in an HDF5 file cannot be read or written partially. The entire contents of the attribute must be read or written in one call.
  • GAUSS functions that take in an HDF5 dataset as a data source (see dstatmt(), glm()), expect the dataset to have an attribute called "headers", containing the variable names of the dataset.

Examples

Create an HDF5 dataset and add headers

// Define file name
fname = "commodities.h5";

// Name of dataset in HDf5 file
dname = "/energy";

// Create an HDF5 dataset with room for 100 observations of 4 variables
call h5create(fname, dname, 100 | 4);

// Variable names for the dataset
attr = "Crude Oil"$|"Gasoline"$|"Heating Oil"$|"Diesel";

// Define a name of the attributes
attr_name = "headers";

// Write attributes to a HDF5 file
call h5writeAttribute(fname, dname, attr_name, attr);

// Read attributes from a HDF5 file
attr_read = h5readAttribute(fname, dname, attr_name);

Add data and calculate descriptive statistics

// Set seed for repeatable random data
rndseed 54235;

// Create 100x4 random normal data
x = rndn(100, 4);

// Write data to dataset created in the example above
call h5write(fname, dname, x);

/*
** Calculate descriptive statistics on some of the variables
** using an hdf5 file schema (h5://filename/dataset)
*/
call dstatmt("h5://commodities.h5/energy", "Gasoline + Heating Oil");
----------------------------------------------------------------------------------
Variable          Mean   Std Dev    Variance   Minimum   Maximum   Valid   Missing
----------------------------------------------------------------------------------

Gasoline        0.0212    1.0130      1.0261   -2.9943    2.3527     100      0
Heating Oil    -0.1120    0.9263      0.8580   -2.7726    3.0910     100      0