Algorithms

Detailed Description

Various algorithms that can be applied to arrays and views.

We can group the different algorithms into

• Algorithms similar to the standard library: nda::all, nda::any, nda::max_element, nda::min_element.
• Reduction algorithms: nda::product, nda::sum.
• Generic algorithm: nda::fold.

Functions
template<Array A>
bool	nda::all (A const &a)
	Do all elements of the array evaluate to true?
template<Array A>
bool	nda::any (A const &a)
	Does any of the elements of the array evaluate to true?
template<Array A, typename F >
auto	nda::fold (F f, A const &a)
	The same as nda::fold, except that the initial value is a default constructed value type of the array.
template<Array A, typename F , typename R >
auto	nda::fold (F f, A const &a, R r)
	Perform a fold operation on the given nda::Array object.
template<Array A>
auto	nda::max_element (A const &a)
	Find the maximum element of an array.
template<Array A>
auto	nda::min_element (A const &a)
	Find the minimum element of an array.
template<Array A> requires (nda::is_scalar_v<get_value_t<A>>)
auto	nda::product (A const &a)
	Multiply all the elements of an nda::Array object.
template<Array A> requires (nda::is_scalar_v<get_value_t<A>>)
auto	nda::sum (A const &a)
	Sum all the elements of an nda::Array object.

Function Documentation

all()

template<Array A>

bool nda::all

(

A const &

a

)

#include <nda/algorithms.hpp>

Do all elements of the array evaluate to true?

The given nda::Array object can also be some lazy expression that evaluates to a boolean. For example:

auto A = nda::array<double, 2>::rand(2, 3);
auto greater0 = nda::map([](auto x) { return x > 0.0; })(A);
auto res = nda::all(greater0);

Template Parameters

A	nda::Array type.

Parameters

a	nda::Array object.

Returns

True if all elements of the array evaluate to true, false otherwise.

Definition at line 113 of file algorithms.hpp.

any()

template<Array A>

bool nda::any

(

A const &

a

)

#include <nda/algorithms.hpp>

Does any of the elements of the array evaluate to true?

The given nda::Array object can also be some lazy expression that evaluates to a boolean. For example:

auto A = nda::array<double, 2>::rand(2, 3);
auto greater05 = nda::map([](auto x) { return x > 0.5; })(A);
auto res = nda::any(greater05);

Template Parameters

A	nda::Array type.

Parameters

a	nda::Array object.

Returns

True if at least one element of the array evaluates to true, false otherwise.

Definition at line 92 of file algorithms.hpp.

fold()

template<Array A, typename F , typename R >

auto nda::fold	(	F	f,
		A const &	a,
		R	r )

#include <nda/algorithms.hpp>

Perform a fold operation on the given nda::Array object.

It calculates the following (where r is an initial value);

auto res = f(...f(f(f(r, a(0,...,0)), a(0,...,1)), a(0,...,2)), ...);

Note

The array is always traversed in C-order.

Template Parameters

A	nda::Array type.
F	Callable type.
R	Type of the initial value.

Parameters

f	Callable object taking two arguments compatible with the initial value and the array value type.
a	nda::Array object.
r	Initial value.

Returns

Result of the fold operation.

Definition at line 63 of file algorithms.hpp.

max_element()

template<Array A>

auto nda::max_element

(

A const &

a

)

#include <nda/algorithms.hpp>

Find the maximum element of an array.

It uses nda::fold and std::max.

Template Parameters

A	nda::Array type.

Parameters

a	nda::Array object.

Returns

Maximum element of the array.

Definition at line 128 of file algorithms.hpp.

min_element()

template<Array A>

auto nda::min_element

(

A const &

a

)

#include <nda/algorithms.hpp>

Find the minimum element of an array.

It uses nda::fold and std::min.

Template Parameters

A	nda::Array type.

Parameters

a	nda::Array object.

Returns

Minimum element of the array.

Definition at line 147 of file algorithms.hpp.

product()

template<Array A>
requires (nda::is_scalar_v<get_value_t<A>>)

auto nda::product

(

A const &

a

)

#include <nda/algorithms.hpp>

Multiply all the elements of an nda::Array object.

Template Parameters

A	nda::Array type.

Parameters

a	nda::Array object.

Returns

Product of all elements.

Definition at line 196 of file algorithms.hpp.

sum()

template<Array A>
requires (nda::is_scalar_v<get_value_t<A>>)

auto nda::sum

(

A const &

a

)

#include <nda/algorithms.hpp>

Sum all the elements of an nda::Array object.

Template Parameters

A	nda::Array type.

Parameters

a	nda::Array object.

Returns

Sum of all elements.

Definition at line 182 of file algorithms.hpp.