- Created by Barbara Jones, last modified on Aug 09, 2019
H5P_SET_DATA_TRANSFORM
Sets a data transform expression
Procedure:
H5P_SET_DATA_TRANSFORM ( plist_id, expression )
Signature:
herr_t H5Pset_data_transform
(hid_t plist_id,
const char *expression)
Fortran90 Interface: h5pset_data_transform_f
SUBROUTINE h5pset_data_transform_f(plist_id, expression, hdferr)
IMPLICIT NONE
INTEGER(HID_T), INTENT(IN) :: plist_id
! Identifier of the property list or class
CHARACTER(LEN=*), INTENT(IN) :: expression
! Buffer to hold transform expression
INTEGER, INTENT(OUT) :: hdferr ! Error code
! 0 on success and -1 on failure
END SUBROUTINE h5pset_data_transform_f
Parameters:
hid_t plist_id | IN: Identifier of the property list or class |
const char *expression | IN: Pointer to the null-terminated data transform expression |
Description:
H5P_SET_DATA_TRANSFORM sets the data transform to be used for reading and writing data. This function operates on the dataset transfer property lists plist_id.
The expression parameter is a string containing an algebraic expression, such as (5/9.0)*(x-32) or x*(x-5). When a dataset is read or written with this property list, the transform expression is applied with the x being replaced by the values in the dataset. When reading data, the values in the file are not changed and the transformed data is returned to the user.
Data transforms can only be applied to integer or floating-point datasets. Order of operations is obeyed and the only supported operations are +, -, *, and /. Parentheses can be nested arbitrarily and can be used to change precedence.
When writing data back to the dataset, the transformed data is written to the file and there is no way to recover the original values to which the transform was applied.
Returns:
Success: a non-negative value
Failure: a negative value
Example:
/* Create the dataset transfer property list */
dxpl_id_f_to_c = H5Pcreate(H5P_DATASET_XFER);
/* Set the data transform */
H5Pset_data_transform(dxpl_id_f_to_c, f_to_c);
/* Read out the data with the data transform */
H5Dread(dataset, H5T_NATIVE_FLOAT, H5S_ALL, H5S_ALL, dxpl_id_f_to_c, windchillC);
! Create the dataset transfer property list and define the ! transform expression. ! CALL h5pcreate_f(H5P_DATASET_XFER_F, dxpl, hdferr) CALL h5pset_data_transform_f (dxpl, transform, hdferr) ! ! Create the dataset using the default properties. Unfortunately ! we must save as a native type or the transform operation will ! fail. ! CALL h5dcreate_f(file, dataset, H5T_NATIVE_INTEGER, space, dset, hdferr) ! ! Write the data to the dataset using the dataset transfer ! property list. ! CALL h5dwrite_f(dset, H5T_NATIVE_INTEGER, wdata, dims, hdferr,xfer_prp=dxpl)
History:
| Release | Change |
|---|---|
| 1.8.0 | Function introduced in this release. |
--- Last Modified: August 09, 2019 | 01:28 PM