apewer-dotnet/Apewer/NumberUtility.cs

using Apewer.Internals;
using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Text;

namespace Apewer
{

    /// <summary>数值实用工具。</summary>
    public static class NumberUtility
    {

        #region 随机数。

        /// <summary>用于生成随机数的时钟位置。</summary>
        private static int RandomSeed = 327680;

        private static float RandomTimer()
        {
            var now = DateTime.Now;
            return (float)((double)(checked((60 * now.Hour + now.Minute) * 60 + now.Second)) + (double)now.Millisecond / 1000.0);
        }

        private static void RandomInit()
        {
            float timer = RandomTimer();
            int num1 = RandomSeed;
            int num2 = BitConverter.ToInt32(BitConverter.GetBytes(timer), 0);
            num2 = ((num2 & 65535) ^ num2 >> 16) << 8;
            num1 = ((num1 & -16776961) | num2);
            RandomSeed = num1;
        }

        /// <summary>生成不大于 1 的随机数，最小为 0。</summary>
        public static float RandomFloat(float max = 1F)
        {
            RandomInit();
            int num1 = RandomSeed;
            if ((double)max != 0.0)
            {
                if ((double)max < 0.0)
                {
                    num1 = BitConverter.ToInt32(BitConverter.GetBytes(max), 0);
                    long vnum2 = (long)num1;
                    vnum2 &= unchecked((long)((ulong)-1));
                    num1 = checked((int)(vnum2 + (vnum2 >> 24) & 16777215L));
                }
                num1 = checked((int)(unchecked((long)num1) * 1140671485L + 12820163L & 16777215L));
            }
            RandomSeed = num1;
            return (float)num1 / 16777216f;
        }

        /// <summary>生成随机整数，包含最小值和最大值。</summary>
        /// <param name="min">最小值。</param>
        /// <param name="max">最大值。</param>
        /// <returns></returns>
        public static int RandomInteger(int max, int min = 0)
        {
            if (max < min)
            {
                var temp = max;
                max = min;
                min = temp;
            }
            float rate = (max - min + 1) * RandomFloat();
            int result = min + (int)rate;
            return result;
        }

        #endregion

        #region Restrict 约束值范围。

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static T RestrictValue<T>(T origin, T min, T max) where T : IComparable
        {
            try
            {
                if (min.CompareTo(max) > 0) return origin;

                if (origin.CompareTo(min) < 0) return min;
                if (origin.CompareTo(max) > 0) return max;
                return origin;
            }
            catch { }

            return origin;
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Byte RestrictValue(Byte target, Byte min, Byte max)
        {
            return RestrictValue<Byte>(target, min, max);
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Int16 RestrictValue(Int16 target, Int16 min, Int16 max)
        {
            return RestrictValue<Int16>(target, min, max);
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Int32 RestrictValue(Int32 target, Int32 min, Int32 max)
        {
            return RestrictValue<Int32>(target, min, max);
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Int64 RestrictValue(Int64 target, Int64 min, Int64 max)
        {
            return RestrictValue<Int64>(target, min, max);
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Single RestrictValue(Single target, Single min, Single max)
        {
            return RestrictValue<Single>(target, min, max);
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Double RestrictValue(Double target, Double min, Double max)
        {
            return RestrictValue<Double>(target, min, max);
        }

        /// <summary>约束值范围，若源值不在范围中，则修改为接近的值。</summary>
        public static Decimal RestrictValue(Decimal target, Decimal min, Decimal max)
        {
            return RestrictValue<Decimal>(target, min, max);
        }

        #endregion

        /// <summary>平均值。</summary>
        public static double Average(params double[] values)
        {
            var amount = 0d;
            foreach (var i in values) amount += i;
            return amount / Convert.ToDouble(values.Length);
        }

        #region 最小值、最大值。

        private static T GetMost<T>(Func<T, T, bool> replace, T[] values)
        {
            if (values == null) return default;

            var length = values.LongLength;
            if (length == 0L) return default;
            if (length == 1L) return values[0L];

            var most = values[0];
            for (var i = 1L; i < length; i++)
            {
                var value = values[i];
                if (value == null) continue;
                if (most == null)
                {
                    most = value;
                }
                else
                {
                    var doReplace = replace(most, value);
                    if (doReplace) most = value;
                }
            }
            return most;
        }

        // 无法输出正确结果。
        // public static T GetMin<T>(params IComparable[] values)
        // {
        //     var result = GetMost((a, b) => a.CompareTo(b) == 1, values);
        //     return result == null ? default : (T)result;
        // }

        // 无法输出正确结果。
        // public static T GetMin<T>(params IComparable<T>[] values)
        // {
        //     var result = GetMost((a, b) => a.CompareTo((T)b) == 1, values);
        //     return result == null ? default : (T)result;
        // }

        // 无法输出正确结果。
        // public static T GetMax<T>(params IComparable[] values)
        // {
        //     var result = GetMost((a, b) => a.CompareTo(b) == -1, values);
        //     return result == null ? default : (T)result;
        // }

        // 无法输出正确结果。
        // public static T GetMax<T>(params IComparable<T>[] values)
        // {
        //     var result = GetMost((a, b) => a.CompareTo((T)b) == -1, values);
        //     return result == null ? default : (T)result;
        // }

        /// <summary>最小值。</summary>
        public static byte Min(params byte[] values) => GetMost((a, b) => a > b, values);

        /// <summary>最小值。</summary>
        public static int Min(params int[] values) => GetMost((a, b) => a > b, values);

        /// <summary>最小值。</summary>
        public static long Min(params long[] values) => GetMost((a, b) => a > b, values);

        /// <summary>最小值。</summary>
        public static float Min(params float[] values) => GetMost((a, b) => a > b, values);

        /// <summary>最小值。</summary>
        public static double Min(params double[] values) => GetMost((a, b) => a > b, values);

        /// <summary>最小值。</summary>
        public static decimal Min(params decimal[] values) => GetMost((a, b) => a > b, values);

        /// <summary>最大值。</summary>
        public static byte Max(params byte[] values) => GetMost((a, b) => a < b, values);

        /// <summary>最大值。</summary>
        public static int Max(params int[] values) => GetMost((a, b) => a < b, values);

        /// <summary>最大值。</summary>
        public static long Max(params long[] values) => GetMost((a, b) => a < b, values);

        /// <summary>最大值。</summary>
        public static float Max(params float[] values) => GetMost((a, b) => a < b, values);

        /// <summary>最大值。</summary>
        public static double Max(params double[] values) => GetMost((a, b) => a < b, values);

        /// <summary>最大值。</summary>
        public static decimal Max(params decimal[] values) => GetMost((a, b) => a < b, values);

        #endregion

        /// <summary>Pearson Correlation Coefficient 皮尔逊相关系数。计算两个数组的相似度。数组长度不相等时，以 0 填充不足的长度。</summary>
        /// <remarks>
        /// <para>0.8 ~ 1.0 : 极强相关</para>
        /// <para>0.6 ~ 0.8 : 强相关</para>
        /// <para>0.4 ~ 0.6 : 中等程度相关</para>
        /// <para>0.2 ~ 0.4 : 弱相关</para>
        /// <para>0.0 ~ 0.2 : 极弱相关或无相关</para>
        /// </remarks>
        /// <exception cref="ArgumentException"></exception>
        public static double Pearson(double[] bytes1, double[] bytes2)
        {
            var length1 = bytes1 == null ? 0L : bytes1.LongLength;
            var length2 = bytes2 == null ? 0L : bytes2.LongLength;
            var length = Math.Max(length1, length2);
            if (length < 1) return 1D;

            var x = new double[length];
            var y = new double[length];
            for (var i = 0L; i < length; i++)
            {
                if (i < length1) x[i] = bytes1[i];
                if (i < length2) y[i] = bytes2[i];
            }

            int n = x.Length; // 数组长度。
            double s = 0d; // 分子。
            double m1 = 0d, m2 = 0d; // 分母。

            double xa = Average(x);
            double ya = Average(y);
            for (int i = 0; i < n; i++)
            {
                s += (x[i] - xa) * (y[i] - ya);
                m1 += Math.Pow(x[i] - xa, 2);
                m2 += Math.Pow(y[i] - ya, 2);
            }

            double r = s / (Math.Sqrt(m1) * Math.Sqrt(m2));
            return r;
        }

    }

}