numeric.h

/**
* @brief wrappers over standard algorithms, to minimize code size, and make more readable
* @brief cross-platform one-file C++ header
*
* @author Sergey Masuryan
* Contact Telegram: @SergeyJames
*
*/
#pragma once
#include <numeric>

namespace wrp {
	
	/**
	 *  @brief        : calculate average value in the range [first,last) (container c) using operator+()
	 *  @required     : InputIt must meet the requirements of LegacyInputIterator.
	 *  @complexity   : At most last - first applications of the predicate
	 *  @return value : average value (default is float) 
	**/
	template<class C, class T = float>
	inline constexpr T average(const C & c, T v = 0.0f) noexcept {
		return c.empty() ? static_cast<T>(0) : std::accumulate(c.cbegin(), c.cend(), v) / static_cast<T>(c.size());
	}

	template<class C, class T = float>
	inline constexpr T average(C && c, T v = 0.0f) noexcept {
		return c.empty() ? static_cast<T>(0) : std::accumulate(c.cbegin(), c.cend(), v) / static_cast<T>(c.size());
	}


	/**
	 *  @brief        : calculate average value in the range [first,last) using operator+()
	 *  @required     : InputIt must meet the requirements of LegacyInputIterator.
	 *  @complexity   : At most last - first applications of the predicate
	 *  @return value : average value (default is float) 
	**/
	template<class Init, class T = float>
	inline constexpr T average(Init _begin, Init _end, T v = 0.0f) noexcept {
		return _begin == _end ? 0.0 : std::accumulate(_begin, _end, v) / static_cast<T>(_end - _begin);
	}


	/**
	 *  @brief        : In statistics and probability theory, a median is a value separating the higher half from the lower half of a data sample
	 * 	@required     : InputIt must meet the requirements of LegacyInputIterator.
	 * 	@complexity   : At most last - first applications of the predicate
	 * 	@return value : median value (default is float) 
	**/
	template<class Init, class T = float>
	inline constexpr T median(Init _begin, Init _end, T v = 0.0f) noexcept {
		if (!std::is_sorted(_begin, _end)) {
			std::sort(_begin, _end);
		}
		return *(_begin + (_end - _begin) / 2);
	}


	/**
	 *  @brief        : calculate number of digits(only signed integral types, and not more than INT64_MAX)
	 *  @complexity   : Logarithmic
	 *  @return value : number of digits, min val is 1 max cal is 19 (INT64_MAX)
	**/
	inline constexpr unsigned short number_of_digits(int64_t a) noexcept {
		short n = 1;
		while ((a /= 10) > 0) ++n;
		return n;
	}

} // !namespace wrp