Template Function thrust::stable_sort_by_key(RandomAccessIterator1, RandomAccessIterator1, RandomAccessIterator2, StrictWeakOrdering)

Function Documentation

template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename StrictWeakOrdering>
void thrust::stable_sort_by_key(RandomAccessIterator1 keys_first, RandomAccessIterator1 keys_last, RandomAccessIterator2 values_first, StrictWeakOrdering comp)

stable_sort_by_key performs a key-value sort. That is, stable_sort_by_key sorts the elements in [keys_first, keys_last) and [values_first, values_first + (keys_last - keys_first)) into ascending key order, meaning that if i and j are any two valid iterators in [keys_first, keys_last) such that i precedes j, and p and q are iterators in [values_first, values_first + (keys_last - keys_first)) corresponding to i and j respectively, then *j is not less than *i.

As the name suggests, stable_sort_by_key is stable: it preserves the relative ordering of equivalent elements. That is, if x and y are elements in [keys_first, keys_last) such that x precedes y, and if the two elements are equivalent (neither x < y nor y < x) then a postcondition of stable_sort_by_key is that x still precedes y.

This version of stable_sort_by_key compares key objects using the function object comp.

The following code snippet demonstrates how to use

sort_by_key to sort an array of character values using integers as sorting keys. The keys are sorted in descending order using the greater<int> comparison operator.
Pre

The range [keys_first, keys_last)) shall not overlap the range [values_first, values_first + (keys_last - keys_first)).

Parameters

  • keys_first: The beginning of the key sequence.

  • keys_last: The end of the key sequence.

  • values_first: The beginning of the value sequence.

  • comp: Comparison operator.

Template Parameters

  • RandomAccessIterator1: is a model of Random Access Iterator, RandomAccessIterator1 is mutable, and RandomAccessIterator1's value_type is convertible to StrictWeakOrdering's first_argument_type and second_argument_type.

  • RandomAccessIterator2: is a model of Random Access Iterator, and RandomAccessIterator2 is mutable.

  • StrictWeakOrdering: is a model of Strict Weak Ordering.

#include <thrust/sort.h>
...
const int N = 6;
int    keys[N] = {  1,   4,   2,   8,   5,   7};
char values[N] = {'a', 'b', 'c', 'd', 'e', 'f'};
thrust::stable_sort_by_key(keys, keys + N, values, thrust::greater<int>());
// keys is now   {  8,   7,   5,   4,   2,   1}
// values is now {'d', 'f', 'e', 'b', 'c', 'a'}

See

http://www.sgi.com/tech/stl/sort.html

See

sort_by_key

See

stable_sort