gko::index_set< IndexType > Class Template Reference

#include <ginkgo/core/base/index_set.hpp>

Public Types
using	index_type = IndexType

Public Member Functions
	index_set (std::shared_ptr< const Executor > exec) noexcept
	index_set (std::shared_ptr< const gko::Executor > exec, std::initializer_list< IndexType > init_list, const bool is_sorted=false)
	index_set (std::shared_ptr< const gko::Executor > exec, const index_type size, const gko::array< index_type > &indices, const bool is_sorted=false)
	index_set (std::shared_ptr< const Executor > exec, const index_set &other)
	index_set (const index_set &other)
	index_set (std::shared_ptr< const Executor > exec, index_set &&other)
	index_set (index_set &&other)
index_set &	operator= (const index_set &other)
index_set &	operator= (index_set &&other)
void	clear () noexcept
std::shared_ptr< const Executor >	get_executor () const
index_type	get_size () const
bool	is_contiguous () const
index_type	get_num_elems () const
index_type	get_global_index (index_type local_index) const
index_type	get_local_index (index_type global_index) const
array< index_type >	map_local_to_global (const array< index_type > &local_indices, const bool is_sorted=false) const
array< index_type >	map_global_to_local (const array< index_type > &global_indices, const bool is_sorted=false) const
array< index_type >	to_global_indices () const
array< bool >	contains (const array< index_type > &global_indices, const bool is_sorted=false) const
bool	contains (const index_type global_index) const
index_type	get_num_subsets () const
const index_type *	get_subsets_begin () const
const index_type *	get_subsets_end () const
const index_type *	get_superset_indices () const

Detailed Description

template<typename IndexType = int32>
class gko::index_set< IndexType >

An index set class represents an ordered set of intervals. The index set contains subsets which store the starting and end points of a range, [a,b), storing the first index and one past the last index. As the index set only stores the end-points of ranges, it can be quite efficient in terms of storage.

This class is particularly useful in storing continuous ranges. For example, consider the index set (1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 18, 19, 20, 21, 42). Instead of storing the entire array of indices, one can store intervals ([1,9), [10,13), [18,22), [42,43)), thereby only using half the storage.

We store three arrays, one (subsets_begin) with the starting indices of the subsets in the index set, another (subsets_end) storing one index beyond the end indices of the subsets and the last (superset_cumulative_indices) storing the cumulative number of indices in the subsequent subsets with an initial zero which speeds up the querying. Additionally, the arrays containing the range boundaries (subsets_begin, subsets_end) are stored in a sorted fashion.

Therefore the storage would look as follows

‍index_set = (1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 18, 19, 20, 21, 42) subsets_begin = {1, 10, 18, 42} subsets_end = {9, 13, 22, 43} superset_cumulative_indices = {0, 8, 11, 15, 16}

Template Parameters

index_type

type of the indices being stored in the index set.

Member Typedef Documentation

index_type

template<typename IndexType = int32>

using gko::index_set< IndexType >::index_type = IndexType

The type of elements stored in the index set.

Constructor & Destructor Documentation

index_set() [1/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( std::shared_ptr< const Executor >  exec )

inlineexplicitnoexcept

Creates an empty index_set tied to the specified Executor.

Parameters

exec	the Executor where the index_set data is allocated

index_set() [2/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( std::shared_ptr< const gko::Executor >  exec, std::initializer_list< IndexType >  init_list, const bool  is_sorted = false  )

inlineexplicit

Creates an index set on the specified executor from the initializer list.

Parameters

exec	the Executor where the index set data will be allocated
init_list	the indices that the index set should hold in an initializer_list.
is_sorted	a parameter that specifies if the indices array is sorted or not. true if sorted.

References gko::index_set< IndexType >::get_executor().

index_set() [3/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( std::shared_ptr< const gko::Executor >  exec, const index_type  size, const gko::array< index_type > &  indices, const bool  is_sorted = false  )

inlineexplicit

Creates an index set on the specified executor and the given size

Parameters

exec	the Executor where the index set data will be allocated
size	the maximum index the index set it allowed to hold. This is the size of the index space.
indices	the indices that the index set should hold.
is_sorted	a parameter that specifies if the indices array is sorted or not. true if sorted.

References gko::array< ValueType >::get_size().

index_set() [4/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( std::shared_ptr< const Executor >  exec, const index_set< IndexType > &  other  )

inline

Creates a copy of the input index_set on a different executor.

Parameters

exec	the executor where the new index_set will be created
other	the index_set to copy from

index_set() [5/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( const index_set< IndexType > &  other )

inline

Creates a copy of the input index_set.

Parameters

other

the index_set to copy from

index_set() [6/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( std::shared_ptr< const Executor >  exec, index_set< IndexType > &&  other  )

inline

Moves the input index_set to a different executor.

Parameters

exec	the executor where the new index_set will be moved to
other	the index_set to move from

index_set() [7/7]

template<typename IndexType = int32>

gko::index_set< IndexType >::index_set ( index_set< IndexType > &&  other )

inline

Moves the input index_set.

Parameters

other

the index_set to move from

Member Function Documentation

clear()

template<typename IndexType = int32>

void gko::index_set< IndexType >::clear ( )

inlinenoexcept

Deallocates all data used by the index_set.

The index_set is left in a valid, but empty state, so the same index_set can be used to allocate new memory. Calls to index_set::get_subsets_begin() will return a nullptr.

References gko::array< ValueType >::clear().

contains() [1/2]

template<typename IndexType = int32>

array< bool > gko::index_set< IndexType >::contains	(	const array< index_type > &	global_indices,
		const bool	is_sorted = false
	)		const

Checks if the individual global indeices exist in the index set.

Parameters

global_indices	the indices to check.
is_sorted	a parameter that specifies if the query array is sorted or not. true if sorted.

Returns

the array that contains element wise whether the corresponding global index in the index set or not.

contains() [2/2]

template<typename IndexType = int32>

bool gko::index_set< IndexType >::contains

(

const index_type

global_index

)

const

Checks if the global index exists in the index set.

Parameters

global_index

the index to check.

Returns

whether the element exists in the index set.

Warning

This single entry query can have significant kernel launch overheads and should be avoided if possible.

get_executor()

template<typename IndexType = int32>

std::shared_ptr< const Executor > gko::index_set< IndexType >::get_executor ( ) const

inline

Returns the executor of the index_set

Returns

the executor.

Referenced by gko::index_set< IndexType >::index_set().

get_global_index()

template<typename IndexType = int32>

index_type gko::index_set< IndexType >::get_global_index

(

index_type

local_index

)

const

Return the global index given a local index.

Consider the set idx_set = (0, 1, 2, 4, 6, 7, 8, 9). This function returns the element at the global index k stored in the index set. For example, idx_set.get_global_index(0) == 0 idx_set.get_global_index(3) == 4 and idx_set.get_global_index(7) == 9

Note

This function returns a scalar value and needs a scalar value. For repeated queries, it is more efficient to use the array functions that take and return arrays which allow for more throughput.

Parameters

local_index

the local index.

Returns

the global index from the index set.

Warning

This single entry query can have significant kernel launch overheads and should be avoided if possible.

get_local_index()

template<typename IndexType = int32>

index_type gko::index_set< IndexType >::get_local_index

(

index_type

global_index

)

const

Return the local index given a global index.

Consider the set idx_set = (0, 1, 2, 4, 6, 7, 8, 9). This function returns the local index in the index set of the provided index set. For example, idx_set.get_local_index(0) == 0 idx_set.get_local_index(4) == 3 and idx_set.get_local_index(6) == 4.

Note

This function returns a scalar value and needs a scalar value. For repeated queries, it is more efficient to use the array functions that take and return arrays which allow for more throughput.

Parameters

global_index

the global index.

Returns

the local index of the element in the index set.

Warning

This single entry query can have significant kernel launch overheads and should be avoided if possible.

get_num_elems()

template<typename IndexType = int32>

index_type gko::index_set< IndexType >::get_num_elems ( ) const

inline

Return the actual number of indices stored in the index set

Returns

number of indices stored in the index set

get_num_subsets()

template<typename IndexType = int32>

index_type gko::index_set< IndexType >::get_num_subsets ( ) const

inline

Returns the number of subsets stored in the index set.

Returns

the number of stored subsets.

References gko::array< ValueType >::get_size().

Referenced by gko::index_set< IndexType >::is_contiguous().

get_size()

template<typename IndexType = int32>

index_type gko::index_set< IndexType >::get_size ( ) const

inline

Returns the size of the index set space.

Returns

the size of the index set space.

get_subsets_begin()

template<typename IndexType = int32>

const index_type * gko::index_set< IndexType >::get_subsets_begin ( ) const

inline

Returns a pointer to the beginning indices of the subsets.

Returns

a pointer to the beginning indices of the subsets.

References gko::array< ValueType >::get_const_data().

get_subsets_end()

template<typename IndexType = int32>

const index_type * gko::index_set< IndexType >::get_subsets_end ( ) const

inline

Returns a pointer to the end indices of the subsets.

Returns

a pointer to the end indices of the subsets.

References gko::array< ValueType >::get_const_data().

get_superset_indices()

template<typename IndexType = int32>

const index_type * gko::index_set< IndexType >::get_superset_indices ( ) const

inline

Returns a pointer to the cumulative indices of the superset of the subsets.

Returns

a pointer to the cumulative indices of the superset of the subsets.

References gko::array< ValueType >::get_const_data().

is_contiguous()

template<typename IndexType = int32>

bool gko::index_set< IndexType >::is_contiguous ( ) const

inline

Returns if the index set is contiguous

Returns

if the index set is contiguous.

References gko::index_set< IndexType >::get_num_subsets().

map_global_to_local()

template<typename IndexType = int32>

array< index_type > gko::index_set< IndexType >::map_global_to_local	(	const array< index_type > &	global_indices,
		const bool	is_sorted = false
	)		const

This is an array version of the scalar function above.

Parameters

global_indices	the global index array.
is_sorted	a parameter that specifies if the query array is sorted or not. true if sorted.

Returns

the local index array from the index set.

Note

Whenever possible, passing a sorted array is preferred as the queries can be significantly faster.

map_local_to_global()

template<typename IndexType = int32>

array< index_type > gko::index_set< IndexType >::map_local_to_global	(	const array< index_type > &	local_indices,
		const bool	is_sorted = false
	)		const

This is an array version of the scalar function above.

Parameters

local_indices	the local index array.
is_sorted	a parameter that specifies if the query array is sorted or not. true if sorted .

Returns

the global index array from the index set.

Note

Whenever possible, passing a sorted array is preferred as the queries can be significantly faster.

Passing local indices from [0, size) is equivalent to using the @to_global_indices function.

operator=() [1/2]

template<typename IndexType = int32>

index_set & gko::index_set< IndexType >::operator= ( const index_set< IndexType > &  other )

inline

Copies data from another index_set

The executor of this is preserved. In case this does not have an assigned executor, it will inherit the executor of other.

Parameters

other

the index_set to copy from

Returns

this

operator=() [2/2]

template<typename IndexType = int32>

index_set & gko::index_set< IndexType >::operator= ( index_set< IndexType > &&  other )

inline

Moves data from another index_set

The executor of this is preserved. In case this does not have an assigned executor, it will inherit the executor of other.

Parameters

other

the index_set to move from

Returns

this

to_global_indices()

template<typename IndexType = int32>

array< index_type > gko::index_set< IndexType >::to_global_indices

(

)

const

This function allows the user obtain a decompressed global_indices array from the indices stored in the index set

Returns

the decompressed set of indices.

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

• ginkgo/core/base/index_set.hpp