std::transform_exclusive_scan

`<numeric>`
	(1)
`template< class InputIt, class OutputIt, class T, class BinaryOperation, class UnaryOperation> OutputIt transform_exclusive_scan( InputIt first, InputIt last, OutputIt d_first, T init, BinaryOperation binary_op, UnaryOperation unary_op);`			(C++17) (C++20)
`template< class InputIt, class OutputIt, class T, class BinaryOperation, class UnaryOperation> constexpr OutputIt transform_exclusive_scan( InputIt first, InputIt last, OutputIt d_first, T init, BinaryOperation binary_op, UnaryOperation unary_op);`			(C++20)
`template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2, class T, class BinaryOperation, class UnaryOperation > ForwardIt2 transform_exclusive_scan( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first, T init, BinaryOperation binary_op, UnaryOperation unary_op );`		(2)	(C++17)

[first, last) unary_op init binary_op exclusive prefix sum d_first exclusive i i

$[first, first + (i - d_first))$ j binary_op init, unary_op(*j)... $[d_first, d_first + (last - first))$ i

$GNSUM(op, a 1, ..., a N)$

$N=1$ $a 1$
$N > 1$ $1 < K+1 = M N$ K $op(GNSUM(op, a 1, ..., a K), GNSUM(op, a M, ..., a N))$

binary_op

(2) policy std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> true

unary_op binary_op $[first, last)$ $[d_first, d_first + (last - first))$ ()

first, last	-
d_first	-	`first`
policy	-
init	-
unary_op	-	FunctionObject `binary_op`
binary_op	-	`unary_op` `binary_op` `init` FunctionObject

- `InputIt` LegacyInputIterator
- `OutputIt` LegacyOutputIterator
- `ForwardIt1, ForwardIt2` LegacyForwardIterator
- `T` MoveConstructible `binary_op(init, unary_op(first))binary_op(init, init)` `binary_op(unary_op(first), unary_op(*first))` `T`

$O(last - first)$ binary_op unary_op

ExecutionPolicy

ExecutionPolicy std::terminate ExecutionPolicy
std::bad_alloc

unary_op init

Run this code

#include <functional>
#include <iostream>
#include <iterator>
#include <numeric>
#include <vector>

int times_10(int x)
{
  return x * 10;
}

int main()
{
  std::vector data {3, 1, 4, 1, 5, 9, 2, 6};

  std::cout << "10 times exclusive sum: ";
  std::transform_exclusive_scan(data.begin(), data.end(),
				std::ostream_iterator<int>(std::cout, " "),
				0, std::plus<int>{}, times_10);
  std::cout << "\n10 times inclusive sum: ";
  std::transform_inclusive_scan(data.begin(), data.end(),
				std::ostream_iterator<int>(std::cout, " "),
				std::plus<int>{}, times_10);
}

:

10 times exclusive sum: 0 30 40 80 90 140 230 250 
10 times inclusive sum: 30 40 80 90 140 230 250 310

partial_sum	() [edit]
exclusive_scan (C++17)	std::inclusive_scan i i () [edit]
transform_inclusive_scan (C++17)	inclusive scan () [edit]






(C++20)





(C++20)




(C++17)
(C++11)
(C++11)
(C++11)

cppreference.com

std::transform_exclusive_scan