Computes whether one row is lexicographically less than another row. More...

Public Member Functions
	row_lexicographic_comparator (Nullate has_nulls, table_device_view lhs, table_device_view rhs, order const column_order=nullptr, null_order const null_precedence=nullptr)
	Construct a function object for performing a lexicographic comparison between the rows of two tables. More...

bool	operator() (size_type lhs_index, size_type rhs_index) const noexcept
	Checks whether the row at `lhs_index` in the `lhs` table compares lexicographically less than the row at `rhs_index` in the `rhs` table. More...

Detailed Description

template<typename Nullate>
class cudf::row_lexicographic_comparator< Nullate >

Computes whether one row is lexicographically less than another row.

Lexicographic ordering is determined by:

Two rows are compared element by element.
The first mismatching element defines which row is lexicographically less or greater than the other.

Lexicographic ordering is exactly equivalent to doing an alphabetical sort of two words, for example, aac would be less than (or precede) abb. The second letter in both words is the first non-equal letter, and a < b, thus aac < abb.

Template Parameters

Nullate A cudf::nullate type describing how to check for nulls.

Definition at line 382 of file row_operators.cuh.

Constructor & Destructor Documentation

◆ row_lexicographic_comparator()

template<typename Nullate >

cudf::row_lexicographic_comparator< Nullate >::row_lexicographic_comparator	(	Nullate	has_nulls,
		table_device_view	lhs,
		table_device_view	rhs,
		order const *	column_order = `nullptr`,
		null_order const *	null_precedence = `nullptr`
	)

inline

Construct a function object for performing a lexicographic comparison between the rows of two tables.

Behavior is undefined if called with incomparable column types.

Exceptions

cudf::logic_error if lhs.num_columns() != rhs.num_columns()

Parameters

has_nulls	Indicates if either input table contains columns with nulls.
lhs	The first table
rhs	The second table (may be the same table as `lhs`)
column_order	Optional, device array the same length as a row that indicates the desired ascending/descending order of each column in a row. If `nullptr`, it is assumed all columns are sorted in ascending order.
null_precedence	Optional, device array the same length as a row and indicates how null values compare to all other for every column. If it is nullptr, then null precedence would be `null_order::BEFORE` for all columns.

Definition at line 403 of file row_operators.cuh.

Member Function Documentation

◆ operator()()

template<typename Nullate >

bool cudf::row_lexicographic_comparator< Nullate >::operator()	(	size_type	lhs_index,
		size_type	rhs_index
	)		const

inlinenoexcept

Checks whether the row at lhs_index in the lhs table compares lexicographically less than the row at rhs_index in the rhs table.

Parameters

lhs_index	The index of the row in the `lhs` table to examine
rhs_index	The index of the row in the `rhs` table to examine

Returns: true if row from the lhs table compares less than row in the rhs table

Definition at line 426 of file row_operators.cuh.

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

row_operators.cuh