thrust::sort_by_key

Defined in thrust/sort.h

template<typename DerivedPolicy, typename RandomAccessIterator1, typename RandomAccessIterator2> void thrust::sort_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, RandomAccessIterator1 keys_first, RandomAccessIterator1 keys_last, RandomAccessIterator2 values_first)

sort_by_key performs a key-value sort. That is, 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.

Note: sort_by_key is not guaranteed to be stable. That is, suppose that *i and *j are equivalent: neither one is less than the other. It is not guaranteed that the relative order of these two keys or the relative order of their corresponding values will be preserved by sort_by_key.

This version of sort_by_key compares key objects using operator<.

The algorithm’s execution is parallelized as determined by exec.

The following code snippet demonstrates how to use sort_by_key to sort an array of character values using integers as sorting keys using the thrust::host execution policy for parallelization:

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