partition#

Overloads#

partition(exec, first, last, pred)#

template<typename DerivedPolicy, typename ForwardIterator, typename Predicate>
ForwardIterator thrust::partition(
const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
ForwardIterator first,
ForwardIterator last,
Predicate pred,
)#

partition reorders the elements [first, last) based on the function object pred, such that all of the elements that satisfy pred precede 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 partition is middle.

Note that the relative order of elements in the two reordered sequences is not necessarily the same as it was in the original sequence. A different algorithm, stable_partition, does guarantee to preserve the relative order.

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

The following code snippet demonstrates how to use partition to reorder a sequence so that even numbers precede odd numbers using the thrust::host execution policy for parallelization:

#include <thrust/partition.h>
#include <thrust/execution_policy.h>
...
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);
thrust::partition(thrust::host,
                  A, A + N,
                  is_even());
// A is now {2, 4, 6, 8, 10, 1, 3, 5, 7, 9}

See also

https://en.cppreference.com/w/cpp/algorithm/partition

See also

stable_partition

See also

partition_copy

Parameters:

  • exec – The execution policy to use for parallelization.

  • first – The beginning of the sequence to reorder.

  • last – The end of the sequence to reorder.

  • pred – A function object which decides to which partition each element of the sequence [first, last) belongs.

Template Parameters:

  • DerivedPolicy – The name of the derived execution policy.

  • ForwardIterator – is a model of Forward Iterator, and ForwardIterator's value_type is convertible to Predicate's argument type, and ForwardIterator is mutable.

  • Predicate – is a model of Predicate.

Returns:

An iterator referring to the first element of the second partition, that is, the sequence of the elements which do not satisfy pred.

partition(first, last, pred)#

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

partition reorders the elements [first, last) based on the function object pred, such that all of the elements that satisfy pred precede 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 partition is middle.

Note that the relative order of elements in the two reordered sequences is not necessarily the same as it was in the original sequence. A different algorithm, stable_partition, does guarantee to preserve the relative order.

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

#include <thrust/partition.h>
...
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);
thrust::partition(A, A + N,
                   is_even());
// A is now {2, 4, 6, 8, 10, 1, 3, 5, 7, 9}

See also

https://en.cppreference.com/w/cpp/algorithm/partition

See also

stable_partition

See also

partition_copy

Parameters:

  • first – The beginning of the sequence to reorder.

  • last – The end of the sequence to reorder.

  • pred – A function object which decides to which partition each element of the sequence [first, last) belongs.

Template Parameters:

  • ForwardIterator – is a model of Forward Iterator, and ForwardIterator's value_type is convertible to Predicate's argument type, and ForwardIterator is mutable.

  • Predicate – is a model of Predicate.

Returns:

An iterator referring to the first element of the second partition, that is, the sequence of the elements which do not satisfy pred.

partition(exec, first, last, stencil, pred)#

template<typename DerivedPolicy, typename ForwardIterator, typename InputIterator, typename Predicate>
ForwardIterator thrust::partition(
const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
ForwardIterator first,
ForwardIterator last,
InputIterator stencil,
Predicate pred,
)#

partition reorders the elements [first, last) based on the function object pred applied to a stencil range [stencil, stencil + (last - first)), such that all of the elements whose corresponding stencil element satisfies pred precede all of the elements whose corresponding stencil element fails to satisfy it. The postcondition is that, for some iterator middle in the range [first, last), pred(*stencil_i) is true for every iterator stencil_i in the range [stencil,stencil + (middle - first)) and false for every iterator stencil_i in the range [stencil + (middle - first), stencil + (last - first)). The return value of stable_partition is middle.

Note that the relative order of elements in the two reordered sequences is not necessarily the same as it was in the original sequence. A different algorithm, stable_partition, does guarantee to preserve the relative order.

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

The following code snippet demonstrates how to use partition to reorder a sequence so that even numbers precede odd numbers using the thrust::host execution policy for parallelization:

#include <thrust/partition.h>
#include <thrust/execution_policy.h>
...
struct is_even
{
  __host__ __device__
  bool operator()(const int &x)
  {
    return (x % 2) == 0;
  }
};
...
int A[] = {0, 1, 0, 1, 0, 1, 0, 1, 0,  1};
int S[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
const int N = sizeof(A)/sizeof(int);
thrust::partition(thrust::host, A, A + N, S, is_even());
// A is now {1, 1, 1, 1, 1, 0, 0, 0, 0, 0}
// S is unmodified

See also

https://en.cppreference.com/w/cpp/algorithm/partition

See also

stable_partition

See also

partition_copy

Parameters:

  • exec – The execution policy to use for parallelization.

  • first – The beginning of the sequence to reorder.

  • last – The end of the sequence to reorder.

  • stencil – The beginning of the stencil sequence.

  • pred – A function object which decides to which partition each element of the sequence [first, last) belongs.

Template Parameters:

  • DerivedPolicy – The name of the derived execution policy.

  • ForwardIterator – is a model of Forward Iterator, and ForwardIterator is mutable.

  • InputIterator – is a model of Input Iterator, and InputIterator's value_type is convertible to Predicate's argument type.

  • Predicate – is a model of Predicate.

Returns:

An iterator referring to the first element of the second partition, that is, the sequence of the elements whose stencil elements do not satisfy pred.

Pre:

The ranges [first,last) and [stencil, stencil + (last - first)) shall not overlap.

partition(first, last, stencil, pred)#

template<typename ForwardIterator, typename InputIterator, typename Predicate>
ForwardIterator thrust::partition(
ForwardIterator first,
ForwardIterator last,
InputIterator stencil,
Predicate pred,
)#

partition reorders the elements [first, last) based on the function object pred applied to a stencil range [stencil, stencil + (last - first)), such that all of the elements whose corresponding stencil element satisfies pred precede all of the elements whose corresponding stencil element fails to satisfy it. The postcondition is that, for some iterator middle in the range [first, last), pred(*stencil_i) is true for every iterator stencil_i in the range [stencil,stencil + (middle - first)) and false for every iterator stencil_i in the range [stencil + (middle - first), stencil + (last - first)). The return value of stable_partition is middle.

Note that the relative order of elements in the two reordered sequences is not necessarily the same as it was in the original sequence. A different algorithm, stable_partition, does guarantee to preserve the relative order.

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

#include <thrust/partition.h>
...
struct is_even
{
  __host__ __device__
  bool operator()(const int &x)
  {
    return (x % 2) == 0;
  }
};
...
int A[] = {0, 1, 0, 1, 0, 1, 0, 1, 0,  1};
int S[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
const int N = sizeof(A)/sizeof(int);
thrust::partition(A, A + N, S, is_even());
// A is now {1, 1, 1, 1, 1, 0, 0, 0, 0, 0}
// S is unmodified

See also

https://en.cppreference.com/w/cpp/algorithm/partition

See also

stable_partition

See also

partition_copy

Parameters:

  • first – The beginning of the sequence to reorder.

  • last – The end of the sequence to reorder.

  • stencil – The beginning of the stencil sequence.

  • pred – A function object which decides to which partition each element of the sequence [first, last) belongs.

Template Parameters:

  • ForwardIterator – is a model of Forward Iterator, and ForwardIterator is mutable.

  • InputIterator – is a model of Input Iterator, and InputIterator's value_type is convertible to Predicate's argument type.

  • Predicate – is a model of Predicate.

Returns:

An iterator referring to the first element of the second partition, that is, the sequence of the elements whose stencil elements do not satisfy pred.

Pre:

The ranges [first,last) and [stencil, stencil + (last - first)) shall not overlap.