std::transform_inclusive_scan

 

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Technical Specifications

 

Algorithm library

Execution policies (C++17)
is_execution_policy	execution::seqexecution::parexecution::par_unseq	execution::sequenced_policyexecution::parallel_policyexecution::parallel_unsequenced_policy
Non-modifying sequence operations
all_ofany_ofnone_of (C++11)(C++11)(C++11) for_each for_each_n (C++17)	countcount_if mismatch equal adjacent_find	findfind_iffind_if_not (C++11) find_end find_first_of	search search_n lexicographical_compare lexicographical_compare_3way (C++20)
Modifying sequence operations
copycopy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) transform	fill fill_n generate generate_n swap iter_swap swap_ranges sample (C++17)	removeremove_if replacereplace_if reverse rotate unique random_shuffle (until C++17)	remove_copyremove_copy_if replace_copyreplace_copy_if reverse_copy rotate_copy unique_copy shuffle (C++11)
Operations on uninitialized storage
uninitialized_copy uninitialized_move (C++17)	uninitialized_copy_n (C++11) uninitialized_move_n (C++17)	uninitialized_fill	uninitialized_fill_n
Partitioning operations
is_partitioned (C++11) partition_point (C++11)	partition partition_copy (C++11)	stable_partition
Sorting operations
is_sorted (C++11) is_sorted_until (C++11)	sort stable_sort	partial_sort partial_sort_copy	nth_element
Binary search operations
lower_bound	upper_bound	binary_search	equal_range
Set operations (on sorted ranges)
merge inplace_merge	set_difference set_intersection	set_symmetric_difference set_union	includes
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is_heap (C++11) is_heap_until (C++11)	make_heap sort_heap	push_heap pop_heap
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max max_element	min min_element	minmax (C++11) minmax_element (C++11)	clamp (C++17) compare_3way (C++20)
Permutations
is_permutation (C++11)	next_permutation	prev_permutation
Numeric operations
iota (C++11) inner_product adjacent_difference	accumulate reduce (C++17) transform_reduce (C++17)	partial_sum inclusive_scan (C++17) exclusive_scan (C++17)	transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
C library
qsort	bsearch

 

Defined in header <numeric>
template< class InputIt, class OutputIt,           class BinaryOperation, class UnaryOperation > OutputIt transform_inclusive_scan( InputIt first, InputIt last, OutputIt d_first,                                    BinaryOperation binary_op, UnaryOperation unary_op );	(1)	(since C++17)
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2,           class BinaryOperation, class UnaryOperation > ForwardIt2 transform_inclusive_scan( ExecutionPolicy&& policy,                                      ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first,                                      BinaryOperation binary_op, UnaryOperation unary_op );	(2)	(since C++17)
template< class InputIt, class OutputIt,           class BinaryOperation, class UnaryOperation, class T > OutputIt transform_inclusive_scan( InputIt first, InputIt last, OutputIt d_first,                                    BinaryOperation binary_op, UnaryOperation unary_op,                                    T init );	(3)	(since C++17)
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2,           class BinaryOperation, class UnaryOperation, class T > ForwardIt2 transform_inclusive_scan( ExecutionPolicy&& policy,                                      ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first,                                      BinaryOperation binary_op, UnaryOperation unary_op,                                      T init );	(4)	(since C++17)

Transforms each element in the range [first, last) with unary_op, then computes an inclusive prefix sum operation using binary_op over the resulting range, optionally with init as the initial value, and writes the results to the range beginning at d_first. "inclusive" means that the i-th input element is included in the i-th sum.

Formally, assigns through each iterator i in [d_first, d_first + (last - first)) the value of

• for overloads (1-2), the generalized noncommutative sum of unary_op(*j)... for every j in [first, first + (i - d_first + 1)) over binary_op,
• for overloads (3-4), the generalized noncommutative sum of init, unary_op(*j)... for every j in [first, first + (i - d_first + 1)) over binary_op,

where generalized noncommutative sum GNSUM(op, a
1, ..., a
N) is defined as follows:

• if N=1, a
  1
• if N > 1, op(GNSUM(op, a
  1, ..., a
  K), GNSUM(op, a
  M, ..., a
  N)) for any K where 1 < K+1 = M ≤ N

In other words, the summation operations may be performed in arbitrary order, and the behavior is nondeterministic if binary_op is not associative.

Overloads (2, 4) are executed according to policy, and do not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true.

unary_op and binary_op shall not invalidate iterators (including the end iterators) or subranges, nor modify elements in the ranges [first, last) or [d_first, d_first + (last - first)). Otherwise, the behavior is undefined.

Parameters

first, last	-	the range of elements to sum
d_first	-	the beginning of the destination range; may be equal to first
policy	-	the execution policy to use. See execution policy for details.
init	-	the initial value
unary_op	-	unary FunctionObject that will be applied to each element of the input range. The return type must be acceptable as input to binary_op.
binary_op	-	binary FunctionObject that will be applied in to the result of unary_op, the results of other binary_op, and init if provided.
Type requirements
- InputIt must meet the requirements of InputIterator.
- OutputIt must meet the requirements of OutputIterator.
- ForwardIt1 must meet the requirements of ForwardIterator. and, if init is not provided, ForwardIt1's value_type must be MoveConstructible and binary_op(unary_op(*first), unary_op(*first)) must be convertible to ForwardIt1's value type
- ForwardIt2 must meet the requirements of ForwardIterator.
- T (if init is provided) must meet the requirements of MoveConstructible. All of binary_op(init, unary_op(*first)), binary_op(init, init), and binary_op(unary_op(*first), unary_op(*first)) must be convertible to T

Return value

Iterator to the element past the last element written.

Complexity

O(last - first) applications of each of binary_op and unary_op.

Exceptions

The overloads with a template parameter named ExecutionPolicy report errors as follows:

• If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the three standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
• If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Notes

unary_op is not applied to init.

The parameter init appears last, differing from std::transform_exclusive_scan, because it is optional for this function.

See also

partial_sum	computes the partial sum of a range of elements (function template)
transform	applies a function to a range of elements (function template)
inclusive_scan (C++17)	similar to std::partial_sum, includes the ith input element in the ith sum (function template)
transform_exclusive_scan (C++17)	applies a functor, then calculates exclusive scan (function template)