Splitting

Files
file	contiguous_split.hpp
	Table APIs for contiguous_split, pack, unpack, and metadata.
file	copying.hpp
	Column APIs for gather, scatter, split, slice, etc.

Classes
struct	cudf::packed_columns
	Column data in a serialized format. More...
struct	cudf::packed_table
	The result(s) of a cudf::contiguous_split. More...

Functions
std::vector< packed_table >	cudf::contiguous_split (cudf::table_view const &input, std::vector< size_type > const &splits, rmm::mr::device_memory_resource *mr=rmm::mr::get_current_device_resource())
	Performs a deep-copy split of a table_view into a vector of packed_table where each packed_table is using a single contiguous block of memory for all of the split's column data. More...
std::vector< column_view >	cudf::split (column_view const &input, host_span< size_type const > splits, rmm::cuda_stream_view stream=cudf::get_default_stream())
	Splits a column_view into a set of column_views according to a set of indices derived from expected splits. More...
std::vector< column_view >	cudf::split (column_view const &input, std::initializer_list< size_type > splits, rmm::cuda_stream_view stream=cudf::get_default_stream())
	Splits a column_view into a set of column_views according to a set of indices derived from expected splits. More...
std::vector< table_view >	cudf::split (table_view const &input, host_span< size_type const > splits, rmm::cuda_stream_view stream=cudf::get_default_stream())
	Splits a table_view into a set of table_views according to a set of indices derived from expected splits. More...
std::vector< table_view >	cudf::split (table_view const &input, std::initializer_list< size_type > splits, rmm::cuda_stream_view stream=cudf::get_default_stream())
	Splits a table_view into a set of table_views according to a set of indices derived from expected splits. More...

Detailed Description

Function Documentation

contiguous_split()

std::vector<packed_table> cudf::contiguous_split	(	cudf::table_view const &	input,
		std::vector< size_type > const &	splits,
		rmm::mr::device_memory_resource *	mr = rmm::mr::get_current_device_resource()
	)

Performs a deep-copy split of a table_view into a vector of packed_table where each packed_table is using a single contiguous block of memory for all of the split's column data.

The memory for the output views is allocated in a single contiguous rmm::device_buffer returned in the packed_table. There is no top-level owning table.

The returned views of input are constructed from a vector of indices, that indicate where each split should occur. The ith returned table_view is sliced as [0, splits[i]) if i=0, else [splits[i], input.size()) if i is the last view and [splits[i-1], splits[i]] otherwise.

For all i it is expected splits[i] <= splits[i+1] <= input.size(). For a splits size N, there will always be N+1 splits in the output.

Note

It is the caller's responsibility to ensure that the returned views do not outlive the viewed device memory contained in the all_data field of the returned packed_table.

Example:
input:   [{10, 12, 14, 16, 18, 20, 22, 24, 26, 28},
          {50, 52, 54, 56, 58, 60, 62, 64, 66, 68}]
splits:  {2, 5, 9}
output:  [{{10, 12}, {14, 16, 18}, {20, 22, 24, 26}, {28}},
          {{50, 52}, {54, 56, 58}, {60, 62, 64, 66}, {68}}]

Exceptions

cudf::logic_error	if splits has end index > size of input.
cudf::logic_error	When the value in splits is not in the range [0, input.size()).
cudf::logic_error	When the values in the splits are 'strictly decreasing'.

Parameters

input	View of a table to split
splits	A vector of indices where the view will be split
mr	An optional memory resource to use for all returned device allocations

Returns

The set of requested views of input indicated by the splits and the viewed memory buffer

split() [1/4]

std::vector<column_view> cudf::split	(	column_view const &	input,
		host_span< size_type const >	splits,
		rmm::cuda_stream_view	stream = cudf::get_default_stream()
	)

Splits a column_view into a set of column_views according to a set of indices derived from expected splits.

The returned view's of input are constructed from vector of splits, which indicates where the split should occur. The ith returned column_view is sliced as [0, splits[i]) if i=0, else [splits[i], input.size()) if i is the last view and [splits[i-1], splits[i]] otherwise.

For all i it is expected splits[i] <= splits[i+1] <= input.size() For a splits size N, there will always be N+1 splits in the output

Note

It is the caller's responsibility to ensure that the returned views do not outlive the viewed device memory.

Example:
input:   {10, 12, 14, 16, 18, 20, 22, 24, 26, 28}
splits:  {2, 5, 9}
output:  {{10, 12}, {14, 16, 18}, {20, 22, 24, 26}, {28}}

Exceptions

cudf::logic_error	if splits has end index > size of input.
cudf::logic_error	When the value in splits is not in the range [0, input.size()).
cudf::logic_error	When the values in the splits are 'strictly decreasing'.

Parameters

input	View of column to split
splits	Indices where the view will be split
stream	CUDA stream used for device memory operations and kernel launches

Returns

The set of requested views of input indicated by the splits

split() [2/4]

std::vector<column_view> cudf::split	(	column_view const &	input,
		std::initializer_list< size_type >	splits,
		rmm::cuda_stream_view	stream = cudf::get_default_stream()
	)

Splits a column_view into a set of column_views according to a set of indices derived from expected splits.

The returned view's of input are constructed from vector of splits, which indicates where the split should occur. The ith returned column_view is sliced as [0, splits[i]) if i=0, else [splits[i], input.size()) if i is the last view and [splits[i-1], splits[i]] otherwise.

For all i it is expected splits[i] <= splits[i+1] <= input.size() For a splits size N, there will always be N+1 splits in the output

Note

It is the caller's responsibility to ensure that the returned views do not outlive the viewed device memory.

Example:
input:   {10, 12, 14, 16, 18, 20, 22, 24, 26, 28}
splits:  {2, 5, 9}
output:  {{10, 12}, {14, 16, 18}, {20, 22, 24, 26}, {28}}

Exceptions

cudf::logic_error	if splits has end index > size of input.
cudf::logic_error	When the value in splits is not in the range [0, input.size()).
cudf::logic_error	When the values in the splits are 'strictly decreasing'.

Parameters

input	View of column to split
splits	Indices where the view will be split
stream	CUDA stream used for device memory operations and kernel launches

Returns

The set of requested views of input indicated by the splits

split() [3/4]

std::vector<table_view> cudf::split	(	table_view const &	input,
		host_span< size_type const >	splits,
		rmm::cuda_stream_view	stream = cudf::get_default_stream()
	)

Splits a table_view into a set of table_views according to a set of indices derived from expected splits.

The returned views of input are constructed from vector of splits, which indicates where the split should occur. The ith returned table_view is sliced as [0, splits[i]) if i=0, else [splits[i], input.size()) if i is the last view and [splits[i-1], splits[i]] otherwise.

For all i it is expected splits[i] <= splits[i+1] <= input.size() For a splits size N, there will always be N+1 splits in the output

Note

It is the caller's responsibility to ensure that the returned views do not outlive the viewed device memory.

Example:
input:   [{10, 12, 14, 16, 18, 20, 22, 24, 26, 28},
          {50, 52, 54, 56, 58, 60, 62, 64, 66, 68}]
splits:  {2, 5, 9}
output:  [{{10, 12}, {14, 16, 18}, {20, 22, 24, 26}, {28}},
          {{50, 52}, {54, 56, 58}, {60, 62, 64, 66}, {68}}]

Exceptions

cudf::logic_error	if splits has end index > size of input.
cudf::logic_error	When the value in splits is not in the range [0, input.size()).
cudf::logic_error	When the values in the splits are 'strictly decreasing'.

Parameters

input	View of a table to split
splits	Indices where the view will be split
stream	CUDA stream used for device memory operations and kernel launches

Returns

The set of requested views of input indicated by the splits

split() [4/4]

std::vector<table_view> cudf::split	(	table_view const &	input,
		std::initializer_list< size_type >	splits,
		rmm::cuda_stream_view	stream = cudf::get_default_stream()
	)

Splits a table_view into a set of table_views according to a set of indices derived from expected splits.

The returned views of input are constructed from vector of splits, which indicates where the split should occur. The ith returned table_view is sliced as [0, splits[i]) if i=0, else [splits[i], input.size()) if i is the last view and [splits[i-1], splits[i]] otherwise.

For all i it is expected splits[i] <= splits[i+1] <= input.size() For a splits size N, there will always be N+1 splits in the output

Note

It is the caller's responsibility to ensure that the returned views do not outlive the viewed device memory.

Example:
input:   [{10, 12, 14, 16, 18, 20, 22, 24, 26, 28},
          {50, 52, 54, 56, 58, 60, 62, 64, 66, 68}]
splits:  {2, 5, 9}
output:  [{{10, 12}, {14, 16, 18}, {20, 22, 24, 26}, {28}},
          {{50, 52}, {54, 56, 58}, {60, 62, 64, 66}, {68}}]

Exceptions

cudf::logic_error	if splits has end index > size of input.
cudf::logic_error	When the value in splits is not in the range [0, input.size()).
cudf::logic_error	When the values in the splits are 'strictly decreasing'.

Parameters

input	View of a table to split
splits	Indices where the view will be split
stream	CUDA stream used for device memory operations and kernel launches

Returns

The set of requested views of input indicated by the splits