using?System;
using?System.Collections.Generic;
using?System.Linq;
using?System.Web;

namespace?HUBU.Statistics
{
????///?

????///?求相關系數的相關靜態方法，包括求均值，標準差，相關系數，離散系數，預警區間
????///?

????public?static?class?Correlation
????{

????????///?

????????///?獲取均值，求傳入數組的算數均值
????????///?

????????public?static?double?GetAverage（double[]?data）
????????{
????????????int?len?=?data.Length;

????????????if?（len?==?0）
????????????????throw?new?Exception（“No?data“）;

????????????double?sum?=?0;

????????????for?（int?i?=?0;?i?????????????????sum?+=?data[i];

????????????return?sum?/?len;
????????}

????????///?

????????///?獲取標準差，求傳入數組的標準差
????????///?

????????public?static?double?GetStdev（double[]?data）
????????{
????????????//?return?Math.Sqrt（GetVariance（data））;
????????????double?x2?=?0;
????????????double?sumx?=?0;
????????????int?n?=?data.Length;
????????????foreach?（double?d?in?data）
????????????{
????????????????x2?+=?d?*?d;
????????????????sumx?+=?d;
????????????}
????????????return?Math.Sqrt（（x2?*?n?-?sumx?*?sumx）?/?（n*（n-1）））;
????????}

????????///?

????????///?求兩列數據的相關系數
????????///?

????????public?static?double?GetCorrelation（double[]?x?double[]?y）
????????{
????????????if?（x.Length?!=?y.Length）
????????????????throw?new?Exception（“Length?of?sources?is?different“）;
????????????double?avgX?=?0;
????????????double?avgY?=?0;
????????????double?sumx?=?0;
????????????double?sumy?=?0;
????????????double?xy?=?0;
????????????double?x2?=?0;
????????????double?y2?=?0;
????????????int?len?=?x.Length;
????????????for?（int?i?=?0;?i?????????????{
????????????????sumx?+=?x[i];
????????????????sumy?+=?y[i];
????????????????xy?+=?x[i]?*?y[i];
????????????????x2?+=?x[i]?*?x[i];
????????????????y2?+=?y[i]?*?y[i];
????????????}
????????????avgX?=?sumx/len;
????????????avgY?=sumy/len;
????????????double?exy?=?xy?/?len;
????????????double?exey?=?avgX?*?avgY;
????????????double?ex2?=?x2?/?len;
????????????double?e2x?=?avgX?*?avgX;
????????????double?ey2?=?y2?/?len;
????????????double?e2y?=?avgY?*?avgY;
????????????double?fm1=?Math.Sqrt（ex2?-?e2x）?;
????????????double?fm2?=Math.Sqrt（ey2?-?e2y）;
????????????return?（exy?-?exey）?/?（fm1?*?fm2）;
????????}

????????///?

????????///?獲取離散系數，求傳入數組的標準差/均值即離散系數。
????????///?

????????///?
????????///?
????????public?static?double?GetCoefficientofVariation（double[]?x）
????????{
????????????double?x2?=?0;
????????????double?sumx?=?0;
????????????int?n?=?x.Length;
????????????foreach?（double?d?in?x）
????????????{
????????????????x2?+=?d?*?d;
????????????????sumx?+=?d;
????????????}
????????????return?Math.Sqrt（（x2?*?n?-?sumx?*?sumx）?/?（n?*?（n?-?1）））?/?（sumx/n）;
????????}
????????
????????///?

????????///?獲取預警區間，（均值-標準差，均值+標準差）
????????///?

????????///?