HighFive::Attribute Class Reference

Class representing an Attribute of a DataSet or Group. More...

#include <H5Attribute.hpp>

Inheritance diagram for HighFive::Attribute:

Collaboration diagram for HighFive::Attribute:

Public Member Functions
std::string	getName () const
	Get the name of the current Attribute.
size_t	getStorageSize () const
	The number of bytes required to store the attribute in the HDF5 file.
DataType	getDataType () const
	Get the DataType of the Attribute.
DataSpace	getSpace () const
	Get the DataSpace of the current Attribute.
DataSpace	getMemSpace () const
	Get the DataSpace of the current Attribute.
template<typename T >
T	read () const
	Get the value of the Attribute.
template<typename T >
void	read (T &array) const
	Get the value of the Attribute in a buffer.
template<typename T >
void	read (T *array, const DataType &mem_datatype) const
	Read the attribute into a pre-allocated buffer.
template<typename T >
void	read (T *array) const
	Read the attribute into a buffer.
template<typename T >
void	read_raw (T *array, const DataType &mem_datatype) const
	Read the attribute into a pre-allocated buffer.
template<typename T >
void	read_raw (T *array) const
	Read the attribute into a buffer. Behaves like Attribute::read(T*, const DataType&) const but additionally this overload deduces the memory datatype from T.
template<typename T >
void	write (const T &value)
	Write the value into the Attribute.
template<typename T >
void	write_raw (const T *buffer, const DataType &mem_datatype)
	Write from a raw pointer.
template<typename T >
void	write_raw (const T *buffer)
	Write from a raw pointer.
AttributeCreateProps	getCreatePropertyList () const
	The create property list used for this attribute.
	Attribute ()=delete
Public Member Functions inherited from HighFive::Object
	Object (Object &&other) noexcept
	~Object ()
bool	isValid () const noexcept
	isValid
hid_t	getId () const noexcept
	getId
ObjectInfo	getInfo () const
	Retrieve several infos about the current object (address, dates, etc)
ObjectType	getType () const
	Gets the fundamental type of the object (dataset, group, etc)
bool	operator== (const Object &other) const noexcept
Public Member Functions inherited from HighFive::PathTraits< Attribute >
	PathTraits ()
std::string	getPath () const
	return the path to the current object
File &	getFile () const noexcept
	Return a reference to the File object this object belongs.

Static Public Attributes
static const ObjectType	type = ObjectType::Attribute

Protected Member Functions
	Object (Object &&other) noexcept
	Object ()
	Object (const Object &other)
	Object (hid_t)
Protected Member Functions inherited from HighFive::Object
	Object ()
	Object (const Object &other)
	Object (hid_t)
Object &	operator= (const Object &other)

Additional Inherited Members
Protected Attributes inherited from HighFive::Object
hid_t	_hid
Protected Attributes inherited from HighFive::PathTraits< Attribute >
std::shared_ptr< File >	_file_obj

Detailed Description

Class representing an Attribute of a DataSet or Group.

See also

AnnotateTraits::createAttribute, AnnotateTraits::getAttribute, AnnotateTraits::listAttributeNames, AnnotateTraits::hasAttribute, AnnotateTraits::deleteAttribute for create, get, list, check or delete Attribute

Constructor & Destructor Documentation

Attribute()

HighFive::Attribute::Attribute ( )

delete

Member Function Documentation

getCreatePropertyList()

AttributeCreateProps HighFive::Attribute::getCreatePropertyList ( ) const

inline

The create property list used for this attribute.

Some of HDF5 properties/setting of an attribute are defined by a create property list. This method returns a copy of the create property list used during creation of the attribute.

auto acpl = attr.getCreatePropertyList();
 
// For example to create another attribute with the same properties.
file.createAttribute("foo", 42, acpl);

Since

2.5.0

getDataType()

DataType HighFive::Attribute::getDataType ( ) const

inline

Get the DataType of the Attribute.

Attribute attr = dset.createAttribute<int>("foo", DataSpace(1, 2));
auto dtype = attr.getDataType(); // Will be an hdf5 type deduced from int

Since

1.0

getMemSpace()

DataSpace HighFive::Attribute::getMemSpace ( ) const

inline

Get the DataSpace of the current Attribute.

Note

This is an alias of getSpace().

Since

1.0

getName()

std::string HighFive::Attribute::getName ( ) const

inline

Get the name of the current Attribute.

auto attr = dset.createAttribute<std::string>("my_attribute", DataSpace::From(string_list));
std::cout << attr.getName() << std::endl; // Will print "my_attribute"

Since

2.2.2

getSpace()

DataSpace HighFive::Attribute::getSpace ( ) const

inline

Get the DataSpace of the current Attribute.

Attribute attr = dset.createAttribute<int>("foo", DataSpace(1, 2));
auto dspace = attr.getSpace(); // This will be a DataSpace of dimension 1 * 2

Since

1.0

getStorageSize()

size_t HighFive::Attribute::getStorageSize ( ) const

inline

The number of bytes required to store the attribute in the HDF5 file.

size_t size = dset.createAttribute<int>("foo", DataSpace(1, 2)).getStorageSize();

Since

1.0

Object() [1/4]

HighFive::Object::Object ( )

inlineprotected

Object() [2/4]

HighFive::Object::Object ( const Object & other )

inlineprotected

Object() [3/4]

HighFive::Object::Object ( hid_t hid )

inlineexplicitprotected

Object() [4/4]

HighFive::Object::Object ( Object && other )

inlineprotectednoexcept

read() [1/4]

template<typename T >

T HighFive::Attribute::read ( ) const

inline

Get the value of the Attribute.

Attribute attr = dset.getAttribute("foo");
// The value will contains what have been written in the attribute
std::vector<int> value = attr.read<std::vector<int>>();

Since

2.5.0

read() [2/4]

template<typename T >

void HighFive::Attribute::read ( T & array ) const

inline

Get the value of the Attribute in a buffer.

Read the attribute into an existing object. Only available for supported types T. If array has preallocated the correct amount of memory, then this routine should not trigger reallocation. Otherwise, if supported, the object will be resized.

An exception is raised if the numbers of dimension of the buffer and of the attribute are different.

// Will read into `value` avoiding memory allocation if the dimensions
// match, i.e. if the attribute `"foo"` has three element.
std::vector<int> value(3);
file.getAttribute("foo").read(value);

Since

1.0

read() [3/4]

template<typename T >

void HighFive::Attribute::read ( T * array ) const

inline

Read the attribute into a buffer.

Deprecated

use read(T& or read_raw.

read() [4/4]

template<typename T >

void HighFive::Attribute::read ( T * array, const DataType & mem_datatype ) const

inline

Read the attribute into a pre-allocated buffer.

Deprecated

use read(T& or read_raw.

read_raw() [1/2]

template<typename T >

void HighFive::Attribute::read_raw ( T * array ) const

inline

Read the attribute into a buffer. Behaves like Attribute::read(T*, const DataType&) const but additionally this overload deduces the memory datatype from T.

Parameters

array

Pointer to the first byte of pre-allocated memory.

Note

If possible prefer either Attribute::read() const or Attribute::read(T&) const.

auto attr = file.getAttribute("foo");
 
// Simulate custom allocation by the application.
size_t n_elements = attr.getSpace().getElementCount();
int * ptr = (int*) malloc(n_elements*sizeof(int));
 
// Read into the pre-allocated memory.
attr.read(ptr);

Since

2.2.2

read_raw() [2/2]

template<typename T >

void HighFive::Attribute::read_raw ( T * array, const DataType & mem_datatype ) const

inline

Read the attribute into a pre-allocated buffer.

Parameters

array	A pointer to the first byte of sufficient pre-allocated memory.
mem_datatype	The DataType of the array.

Note

This is the shallowest wrapper around H5Aread. If possible prefer either Attribute::read() const or Attribute::read(T&) const.

auto attr = file.getAttribute("foo");
 
// Simulate custom allocation by the application.
size_t n_elements = attr.getSpace().getElementCount();
int * ptr = (int*) malloc(n_elements*sizeof(int));
 
// Read into the pre-allocated memory.
attr.read(ptr, mem_datatype);

Since

2.2.2

write()

template<typename T >

void HighFive::Attribute::write ( const T & value )

inline

Write the value into the Attribute.

Write the value to the attribute. For supported types T, this overload will write the value to the attribute. The datatype and dataspace are deduced automatically. However, since the attribute has already been created, the dimensions of value must match those of the attribute.

// Prefer the fused version if creating and writing the attribute
// at the same time.
dset.createAttribute("foo", std::vector<int>{1, 2, 3});
 
// To overwrite the value:
std::vector<int> value{4, 5, 6};
dset.getAttribute<int>("foo").write(value);

Since

1.0

write_raw() [1/2]

template<typename T >

void HighFive::Attribute::write_raw ( const T * buffer )

inline

Write from a raw pointer.

Much like Attribute::write_raw(const T*, const DataType&). Additionally, this overload attempts to automatically deduce the datatype of the buffer. Note, that the file datatype is already set.

Parameters

buffer

Pointer to the first byte.

Note

If possible prefer Attribute::write.

// Simulate the application creating `value` and only exposing access
// to the raw pointer `ptr`.
std::vector<std::array<int, 3>> value{{1, 2, 3}, {4, 5, 6}};
int * ptr = (int*) value.data();
 
// Simply write the bytes to disk.
attr.write(ptr);

Since

2.2.2

write_raw() [2/2]

template<typename T >

void HighFive::Attribute::write_raw ( const T * buffer, const DataType & mem_datatype )

inline

Write from a raw pointer.

Values that have been correctly arranged memory, can be written directly by passing a raw pointer.

Parameters

buffer	Pointer to the first byte of the value.
mem_datatype	The DataType of the buffer.

Note

This is the shallowest wrapper around H5Awrite. It's useful if you need full control. If possible prefer Attribute::write.

Attribute attr = dset.createAttribute<int>("foo", DataSpace(2, 3));
 
// Simulate the application creating `value` and only exposing access
// to the raw pointer `ptr`.
std::vector<std::array<int, 3>> value{{1, 2, 3}, {4, 5, 6}};
int * ptr = (int*) value.data();
 
// Simply write the bytes to disk.
attr.write(ptr, AtomicType<int>());

Since

2.2.2

Member Data Documentation

type

const ObjectType HighFive::Attribute::type = ObjectType::Attribute

static

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The documentation for this class was generated from the following files:

• highfive/H5Attribute.hpp
• highfive/bits/H5Attribute_misc.hpp