贝叶斯猜测性别

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Bayes
{
    public class Bayes
    {
        private static List<NameFrequency> nameFrequencies = new List<NameFrequency>();

        public static void Initialize()
        {
           //get charfreq.csv from https://gist.github.com/qianlifeng/c4470544c8f953043ac9
            var reader = new StreamReader(File.OpenRead(@"charfreq.csv"));
            //skip first line
            reader.ReadLine();

            while (!reader.EndOfStream)
            {
                var line = reader.ReadLine();

                if (!string.IsNullOrEmpty(line))
                {
                    var values = line.Split(',');
                    nameFrequencies.Add(new NameFrequency(values[0], int.Parse(values[1]), int.Parse(values[2])));
                }

            }
        }

        public static GuessResult Guess(string name)
        {
            // P(gender=男|name=本山) 
            //  = P(name=本山|gender=男) * P(gender=男) / P(name=本山)
            //  = P(name has 本|gender=男) * P(name has 山|gender=男) * P(gender=男) / P(name=本山)

            var fullName = name;
            //除掉姓氏干扰
            name = name.Substring(1);

            //算该名字是男生的概率
            double pMale = 1;
            foreach (char c in name)
            {
                NameFrequency cFrequency = nameFrequencies.FirstOrDefault(o => o.Name == c.ToString());
                if (cFrequency != null)
                {
                    pMale *= (double)cFrequency.MaleCount / nameFrequencies.Sum(o => o.MaleCount);
                }
            }

            double pM = nameFrequencies.Sum(o => o.MaleCount) /
                           (double)nameFrequencies.Sum(o => o.MaleCount + o.FeMaleCount);
            pMale *= pM;

            //算该名字是女生的概率
            double pFeMale = 1;
            foreach (char c in name)
            {
                NameFrequency cFrequency = nameFrequencies.FirstOrDefault(o => o.Name == c.ToString());
                if (cFrequency != null)
                {
                    pFeMale *= (double)cFrequency.FeMaleCount / nameFrequencies.Sum(o => o.FeMaleCount);
                }
            }

            pFeMale *= nameFrequencies.Sum(o => o.FeMaleCount) / (double)nameFrequencies.Sum(o => o.MaleCount + o.FeMaleCount);

            return new GuessResult()
            {
                Name = fullName,
                IsMale = pMale > pFeMale,
                Probability = (pMale > pFeMale ? pMale : pFeMale) / (pMale + pFeMale)
            };
        }
    }

    public class NameFrequency
    {
        public NameFrequency()
        {

        }

        public NameFrequency(string name, int maleCount, int femaleCount)
        {
            Name = name;
            MaleCount = maleCount;
            FeMaleCount = femaleCount;
        }

        public string Name { get; set; }

        public int MaleCount { get; set; }

        public int FeMaleCount { get; set; }
    }

    public class GuessResult
    {
        public string Name { get; set; }

        public bool IsMale { get; set; }

        public double Probability { get; set; }

        public override string ToString()
        {
            return "姓名：" + Name + "，性别：" + (IsMale ? "男性" : "女性") + "，概率：" + Math.Round(Probability, 2) * 100 + "%";
        }
    }
}