thrust

◆ stable_partition() [2/4]

template<typename ForwardIterator , typename Predicate >
ForwardIterator thrust::stable_partition ( ForwardIterator  first,
ForwardIterator  last,
Predicate  pred 
)

stable_partition is much like partition : it reorders the elements in the range [first, last) based on the function object pred, such that all of the elements that satisfy pred precede all of the elements that fail to satisfy it. The postcondition is that, for some iterator middle in the range [first, last), pred(*i) is true for every iterator i in the range [first,middle) and false for every iterator i in the range [middle, last). The return value of stable_partition is middle.

stable_partition differs from partition in that stable_partition is guaranteed to preserve relative order. That is, if x and y are elements in [first, last), and stencil_x and stencil_y are the stencil elements in corresponding positions within [stencil, stencil + (last - first)), and pred(stencil_x) == pred(stencil_y), and if x precedes y, then it will still be true after stable_partition that x precedes y.

Parameters
firstThe first element of the sequence to reorder.
lastOne position past the last element of the sequence to reorder.
predA function object which decides to which partition each element of the sequence [first, last) belongs.
Returns
An iterator referring to the first element of the second partition, that is, the sequence of the elements which do not satisfy pred.
Template Parameters
ForwardIteratoris a model of Forward Iterator, and ForwardIterator's value_type is convertible to Predicate's argument_type, and ForwardIterator is mutable.
Predicateis a model of Predicate.

The following code snippet demonstrates how to use stable_partition to reorder a sequence so that even numbers precede odd numbers.

...
struct is_even
{
__host__ __device__
bool operator()(const int &x)
{
return (x % 2) == 0;
}
};
...
int A[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
const int N = sizeof(A)/sizeof(int);
is_even());
// A is now {2, 4, 6, 8, 10, 1, 3, 5, 7, 9}
See also
http://www.sgi.com/tech/stl/stable_partition.html
partition
stable_partition_copy