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
.
- Parameters
-
exec | The execution policy to use for parallelization. |
keys_first | The beginning of the key sequence. |
keys_last | The end of the key sequence. |
values_first | The beginning of the value sequence. |
- Template Parameters
-
DerivedPolicy | The name of the derived execution policy. |
RandomAccessIterator1 | is a model of Random Access Iterator, RandomAccessIterator1 is mutable, and RandomAccessIterator1's value_type is a model of LessThan Comparable, and the ordering relation on RandomAccessIterator1's value_type is a strict weak ordering, as defined in the LessThan Comparable requirements. |
RandomAccessIterator2 | is a model of Random Access Iterator, and RandomAccessIterator2 is mutable. |
- Precondition
- The range
[keys_first, keys_last))
shall not overlap the range [values_first, values_first + (keys_last - keys_first))
.
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:
...
const int N = 6;
int keys[N] = { 1, 4, 2, 8, 5, 7};
char values[N] = {'a', 'b', 'c', 'd', 'e', 'f'};
- See also
- https://en.cppreference.com/w/cpp/algorithm/sort
-
stable_sort_by_key
-
sort