Files
aare/include/aare/algorithm.hpp
2025-06-10 16:09:06 +02:00

112 lines
3.5 KiB
C++

#pragma once
#include <aare/NDArray.hpp>
#include <algorithm>
#include <array>
#include <vector>
namespace aare {
/**
* @brief Index of the last element that is smaller than val.
* Requires a sorted array. Uses >= for ordering. If all elements
* are smaller it returns the last element and if all elements are
* larger it returns the first element.
* @param first iterator to the first element
* @param last iterator to the last element
* @param val value to compare
* @return index of the last element that is smaller than val
*
*/
template <typename T>
size_t last_smaller(const T *first, const T *last, T val) {
for (auto iter = first + 1; iter != last; ++iter) {
if (*iter >= val) {
return std::distance(first, iter - 1);
}
}
return std::distance(first, last - 1);
}
template <typename T> size_t last_smaller(const NDArray<T, 1> &arr, T val) {
return last_smaller(arr.begin(), arr.end(), val);
}
template <typename T> size_t last_smaller(const std::vector<T> &vec, T val) {
return last_smaller(vec.data(), vec.data() + vec.size(), val);
}
/**
* @brief Index of the first element that is larger than val.
* Requires a sorted array. Uses > for ordering. If all elements
* are larger it returns the first element and if all elements are
* smaller it returns the last element.
* @param first iterator to the first element
* @param last iterator to the last element
* @param val value to compare
* @return index of the first element that is larger than val
*/
template <typename T>
size_t first_larger(const T *first, const T *last, T val) {
for (auto iter = first; iter != last; ++iter) {
if (*iter > val) {
return std::distance(first, iter);
}
}
return std::distance(first, last - 1);
}
template <typename T> size_t first_larger(const NDArray<T, 1> &arr, T val) {
return first_larger(arr.begin(), arr.end(), val);
}
template <typename T> size_t first_larger(const std::vector<T> &vec, T val) {
return first_larger(vec.data(), vec.data() + vec.size(), val);
}
/**
* @brief Index of the nearest element to val.
* Requires a sorted array. If there is no difference it takes the first
* element.
* @param first iterator to the first element
* @param last iterator to the last element
* @param val value to compare
* @return index of the nearest element
*/
template <typename T>
size_t nearest_index(const T *first, const T *last, T val) {
auto iter = std::min_element(first, last, [val](T a, T b) {
return std::abs(a - val) < std::abs(b - val);
});
return std::distance(first, iter);
}
template <typename T> size_t nearest_index(const NDArray<T, 1> &arr, T val) {
return nearest_index(arr.begin(), arr.end(), val);
}
template <typename T> size_t nearest_index(const std::vector<T> &vec, T val) {
return nearest_index(vec.data(), vec.data() + vec.size(), val);
}
template <typename T, size_t N>
size_t nearest_index(const std::array<T, N> &arr, T val) {
return nearest_index(arr.data(), arr.data() + arr.size(), val);
}
template <typename T> std::vector<T> cumsum(const std::vector<T> &vec) {
std::vector<T> result(vec.size());
std::partial_sum(vec.begin(), vec.end(), result.begin());
return result;
}
template <typename Container> bool all_equal(const Container &c) {
if (!c.empty() &&
std::all_of(begin(c), end(c),
[c](const typename Container::value_type &element) {
return element == c.front();
}))
return true;
return false;
}
} // namespace aare