H5D: Datasets Interface

Dataset Object API Functions

Name: H5Dcreate

Signature:

hid_t H5Dcreate(hid_t loc_id, const char *name, hid_ttype_id, hid_tspace_id, hid_tcreate_plist_id )

Purpose:

Creates a dataset at the specified location.

Description:

H5Dcreate creates a data set with a name, name, in the file or in the group specified by the identifier loc_id. The dataset has the datatype and dataspace identified by type_id and space_id, respectively. The specified datatype and dataspace are the datatype and dataspace of the dataset as it will exist in the file, which may be different than in application memory. Dataset creation properties are specified by the argument create_plist_id.

create_plist_id is a H5P_DATASET_CREATE property list created with H5Pcreate() and initialized with the various functions described above. H5Dcreate() returns a dataset identifier for success or negative for failure. The identifier should eventually be closed by calling H5Dclose() to release resources it uses.

Parameters:

hid_t loc_id

Identifier of the file or group to create the dataset within.

const char * name

The name of the dataset to create.

hid_t type_id

Identifier of the datatype to use when creating the dataset.

hid_t space_id

Identifier of the dataspace to use when creating the dataset.

hid_t create_plist_id

Identifier of the set creation property list.

Returns:

Returns a dataset identifier if successful; otherwise returns a negative value.

Name: H5Dopen

Signature:

hid_t H5Dopen(hid_t loc_id, const char *name )

Purpose:

Opens an existing dataset.

Description:

H5Dopen opens an existing dataset for access in the file or group specified in loc_id. name is a dataset name and is used to identify the dataset in the file.

Parameters:

hid_t loc_id

Identifier of the dataset to open or the file or group to access the dataset within.

const char * name

The name of the dataset to access.

Returns:

Returns a dataset identifier if successful; otherwise returns a negative value.

Name: H5Dget_space

Signature:

hid_t H5Dget_space(hid_t dataset_id )

Purpose:

Returns an identifier for a copy of the dataspace for a dataset.

Description:

H5Dget_space returns an identifier for a copy of the dataspace for a dataset. The dataspace identifier should be released with the H5Sclose() function.

Parameters:

hid_t dataset_id

Identifier of the dataset to query.

Returns:

Returns a dataspace identifier if successful; otherwise returns a negative value.

Name: H5Dget_type

Signature:

hid_t H5Dget_type(hid_t dataset_id )

Purpose:

Returns an identifier for a copy of the datatype for a dataset.

Description:

H5Dget_type returns an identifier for a copy of the datatype for a dataset. The datatype should be released with the H5Tclose() function.

If a dataset has a named datatype, then an identifier to the opened datatype is returned. Otherwise, the returned datatype is read-only. If atomization of the datatype fails, then the datatype is closed.

Parameters:

hid_t dataset_id

Identifier of the dataset to query.

Returns:

Returns a datatype identifier if successful; otherwise returns a negative value.

Name: H5Dget_create_plist

Signature:

hid_t H5Dget_create_plist(hid_t dataset_id )

Purpose:

Returns an identifier for a copy of the dataset creation property list for a dataset.

Description:

H5Dget_create_plist returns an identifier for a copy of the dataset creation property list for a dataset. The creation property list identifier should be released with the H5Pclose() function.

Parameters:

hid_t dataset_id

Identifier of the dataset to query.

Returns:

Returns a dataset creation property list identifier if successful; otherwise returns a negative value.

Name: H5Dread

Signature:

herr_t H5Dread(hid_t dataset_id, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t xfer_plist_id, void * buf )

Purpose:

Reads raw data from the specified dataset into buf, converting from file datatype and dataspace to memory datatype and dataspace.

Description:

H5Dread reads a (partial) dataset, specified by its identifier dataset_id, from the file into the application memory buffer buf. Data transfer properties are defined by the argument xfer_plist_id. The memory datatype of the (partial) dataset is identified by the identifier mem_type_id. The part of the dataset to read is defined by mem_space_id and file_space_id.

file_space_id can be the constant H5S_ALL, which indicates that the entire file data space is to be referenced.

mem_space_id can be the constant H5S_ALL, in which case the memory data space is the same as the file data space defined when the dataset was created.

The number of elements in the memory data space must match the number of elements in the file data space.

xfer_plist_id can be the constant H5P_DEFAULT, in which case the default data transfer properties are used.

Datatype conversion takes place at the time of a read or write and is automatic. See the Data Conversion section of The Data Type Interface (H5T) in the HDF5 User's Guide for a discussion of data conversion, including the range of conversions currently supported by the HDF5 libraries.

Parameters:

hid_t dataset_id

Identifier of the dataset read from.

hid_t mem_type_id

Identifier of the memory datatype.

hid_t mem_space_id

Identifier of the memory dataspace.

hid_t file_space_id

Identifier of the dataset's dataspace in the file.

hid_t xfer_plist_id

Identifier of a transfer property list for this I/O operation.

void * buf

Buffer to store data read from the file.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5Dwrite

Signature:

herr_t H5Dwrite(hid_t dataset_id, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t xfer_plist_id, const void * buf )

Purpose:

Writes raw data from an application buffer buf to the specified dataset, converting from memory datatype and dataspace to file datatype and dataspace.

Description:

H5Dwrite writes a (partial) dataset, specified by its identifier dataset_id, from the application memory buffer buf into the file. Data transfer properties are defined by the argument xfer_plist_id. The memory datatype of the (partial) dataset is identified by the identifier mem_type_id. The part of the dataset to write is defined by mem_space_id and file_space_id.

file_space_id can be the constant H5S_ALL. which indicates that the entire file data space is to be referenced.

mem_space_id can be the constant H5S_ALL, in which case the memory data space is the same as the file data space defined when the dataset was created.

The number of elements in the memory data space must match the number of elements in the file data space.

xfer_plist_id can be the constant H5P_DEFAULT. in which case the default data transfer properties are used.

Writing to an external dataset will fail if the HDF5 file is not open for writing.

Datatype conversion takes place at the time of a read or write and is automatic. See the Data Conversion section of The Data Type Interface (H5T) in the HDF5 User's Guide for a discussion of data conversion, including the range of conversions currently supported by the HDF5 libraries.

Parameters:

hid_t dataset_id

Identifier of the dataset read from.

hid_t mem_type_id

Identifier of the memory datatype.

hid_t mem_space_id

Identifier of the memory dataspace.

hid_t file_space_id

Identifier of the dataset's dataspace in the file.

hid_t xfer_plist_id

Identifier of a transfer property list for this I/O operation.

const void * buf

Buffer with data to be written to the file.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5Dextend

Signature:

herr_t H5Dextend(hid_t dataset_id, const hsize_t * size )

Purpose:

Extends a dataset with unlimited dimension.

Description:

H5Dextend verifies that the dataset is at least of size size. The dimensionality of size is the same as that of the dataspace of the dataset being changed. This function cannot be applied to a dataset with fixed dimensions.

Parameters:

hid_t dataset_id

Identifier of the dataset.

const hsize_t * size

Array containing the new magnitude of each dimension.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5Dclose

Signature:

hid_t H5Dclose(hid_t dataset_id )

Purpose:

Description:

H5Dclose ends access to a dataset specified by dataset_id and releases resources used by it. Further use of the dataset identifier is illegal in calls to the dataset API.

Parameters:

hid_t dataset_id

Identifier of the dataset to finish access to.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.