thrust::transform_exclusive_scan

Defined in thrust/transform_scan.h

template<typename DerivedPolicy, typename InputIterator, typename OutputIterator, typename UnaryFunction, typename T, typename AssociativeOperator> OutputIterator thrust::transform_exclusive_scan(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator first, InputIterator last, OutputIterator result, UnaryFunction unary_op, T init, AssociativeOperator binary_op)

transform_exclusive_scan fuses the transform and exclusive_scan operations. transform_exclusive_scan is equivalent to performing a tranformation defined by unary_op into a temporary sequence and then performing an exclusive_scan on the tranformed sequence. In most cases, fusing these two operations together is more efficient, since fewer memory reads and writes are required. In transform_exclusive_scan, init is assigned to *result and the result of binary_op(init, unary_op(*first)) is assigned to *(result + 1), and so on. The transform scan operation is permitted to be in-place.

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

The following code snippet demonstrates how to use transform_exclusive_scan using the thrust::host execution policy for parallelization:

#include <thrust/transform_scan.h>
#include <thrust/execution_policy.h>
...

int data[6] = {1, 0, 2, 2, 1, 3};

thrust::negate<int> unary_op;
thrust::plus<int> binary_op;

thrust::transform_exclusive_scan(thrust::host, data, data + 6, data, unary_op, 4, binary_op); // in-place scan

// data is now {4, 3, 3, 1, -1, -2}