c# - 从文件中获取最佳记录

Question

我有一个包含以下文本的文件

mimi,m,70
tata,f,60
bobo,m,100
soso,f,30

I did the reading from file thing and many many other methods and functions, but how I can get the best male name and his grade according to the grade.

here is the code I wrote. Hope it's not so long

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace practice_Ex
{
    class Program
    {
        public static int[] ReadFile(string FileName, out string[] Name, out char[] Gender)
        {
            Name = new string[1];
            int[] Mark = new int[1];
            Gender = new char[1];
            if (File.Exists(FileName))
            {
                FileStream Input = new FileStream(FileName, FileMode.Open, FileAccess.Read);
                StreamReader SR = new StreamReader(Input);
                string[] Current;
                int Counter = 0;
                string Str = SR.ReadLine();
                while (Str != null)
                {
                    Current = Str.Split(',');
                    Name[Counter] = Current[0];
                    Mark[Counter] = int.Parse(Current[2]);
                    Gender[Counter] = char.Parse(Current[1].ToUpper());
                    Counter++;
                    Array.Resize(ref Name, Counter + 1);
                    Array.Resize(ref Mark, Counter + 1);
                    Array.Resize(ref Gender, Counter + 1);
                    Str = SR.ReadLine();
                }
            }
            return Mark;
        }

        public static int MostFreq(int[] M, out int Frequency)
        {
            int Counter = 0;
            int Frequent = 0;
            Frequency = 0;
            for (int i = 0; i < M.Length; i++)
            {
                Counter = 0;
                for (int j = 0; j < M.Length; j++)
                    if (M[i] == M[j])
                        Counter++;
                if (Counter > Frequency)
                {
                    Frequency = Counter;
                    Frequent = M[i];
                }
            }
            return Frequent;
        }

        public static int Avg(int[] M)
        {
            int total = 0;
            for (int i = 0; i < M.Length; i++)
                total += M[i];
            return total / M.Length;
        }

        public static int AvgCond(char[] G, int[] M, char S)
        {
            int total = 0;
            int counter = 0;
            for (int i = 0; i < G.Length; i++)
                if (G[i] == S)
                {
                    total += M[i];
                    counter++;
                }
            return total / counter;
        }

        public static int BelowAvg(int[] M, out int AboveAvg)
        {
            int Bcounter = 0;
            AboveAvg = 0;
            for (int i = 0; i < M.Length; i++)
            {
                if (M[i] < Avg(M))
                    Bcounter++;
                else
                    AboveAvg++;
            }
            return Bcounter;
        }

        public static int CheckNames(string[] Name, char C)
        {
            C = char.Parse(C.ToString().ToLower());
            int counter = 0;
            string Str;
            for (int i = 0; i < Name.Length - 1; i++)
            {
                Str = Name[i].ToLower();
                if (Str[0] == C || Str[Str.Length - 1] == C)
                    counter++;
            }
            return counter;
        }

        public static void WriteFile(string FileName, string[] Output)
        {
            FileStream FS = new FileStream(FileName, FileMode.OpenOrCreate, FileAccess.Write);
            StreamWriter SW = new StreamWriter(FS);
            for (int i = 0; i < Output.Length; i++)
                SW.WriteLine(Output[i]);
        }

        static void Main(string[] args)
        {
            int[] Mark;
            char[] Gender;
            string[] Name;
            string[] Output = new string[8];
            int Frequent, Frequency, AvgAll, MaleAvg, FemaleAvg, BelowAverage, AboveAverage, NamesCheck;
            Mark = ReadFile("c:\\IUST1.txt", out Name, out Gender);
            Frequent = MostFreq(Mark, out Frequency);
            AvgAll = Avg(Mark);
            MaleAvg = AvgCond(Gender, Mark, 'M');
            FemaleAvg = AvgCond(Gender, Mark, 'F');
            BelowAverage = BelowAvg(Mark, out AboveAverage);
            NamesCheck = CheckNames(Name, 'T');
            Output [0]= "Frequent Mark = " + Frequent.ToString();
            Output [1]= "Frequency = " + Frequency.ToString();
            Output [2]= "Average Of All = " + AvgAll.ToString();
            Output [3]= "Average Of Males = " + MaleAvg.ToString();
            Output [4]= "Average Of Females = " + FemaleAvg.ToString();
            Output [5]= "Below Average = " + BelowAverage.ToString();
            Output [6]= "Above Average = " + AboveAverage.ToString();
            Output [7]= "Names With \"T\" = " + NamesCheck.ToString();
            WriteFile("c:\\Output.txt", Output);
        }
    }
}

Answer 1

好吧，我喜欢使用 LINQ(更新:通过评论排除)进行查询，尤其是如果我可以在不缓冲数据的情况下进行查询(这样我就可以有效地处理一个巨大的文件)。例如下面(更新:删除了 LINQ)；请注意迭代器 block (yield return)的使用使这完全“惰性”——一次只有一条记录保存在内存中。

这也显示了关注点分离:一种方法处理逐行读取文件；另一种方法处理逐行读取文件。一种方法处理将一行解析为类型化数据记录；一种(或多种)方法处理这些数据记录。

using System;
using System.Collections.Generic;
using System.IO;

enum Gender { Male, Female, Unknown }
class Record
{
    public string Name { get; set; }
    public Gender Gender { get; set; }
    public int Score { get; set; }
}
static class Program
{
    static IEnumerable<string> ReadLines(string path)
    {
        using (StreamReader reader = File.OpenText(path))
        {
            string line;
            while ((line = reader.ReadLine()) != null)
            {
                yield return line;
            }
        }
    }
    static IEnumerable<Record> Parse(string path)
    {
        foreach (string line in ReadLines(path))
        {
            string[] segments = line.Split(',');
            Gender gender;
            switch(segments[1]) {
                case "m": gender = Gender.Male; break;
                case "f": gender = Gender.Female; break;
                default: gender = Gender.Unknown; break;
            }
            yield return new Record
            {
                Name = segments[0],
                Gender = gender,
                Score = int.Parse(segments[2])
            };
        }
    }
    static void Main()
    {
        Record best = null;
        foreach (Record record in Parse("data.txt"))
        {
            if (record.Gender != Gender.Male) continue;
            if (best == null || record.Score > best.Score)
            {
                best = record;
            }
        }

        Console.WriteLine("{0}: {1}", best.Name, best.Score);
    }
}

将事物编写为迭代器的优点是您可以轻松地使用流式处理或缓冲 - 例如，您可以:

List<Record> data = new List<Record>(Parse("data.txt"));

然后整天操作数据(假设它不是太大)——对多个聚合、变异数据等很有用。