Question

I need a way of finding a matching row in an object list based on multiple key words. In the code example below, the FindID() function is the one I need to implement.

The rules are:

1. Some of the rows in the table have * as the value (wildcard), which means they would match any value.
2. The priority of matching is from left to right (i.e., it is more important to match values on the left side)

Some examples:

FindID("John", "Black", "Brown"); – should return 1, complete match

FindID("John", "Red", "Green"); – should return 5 (not 7), matched on “John” and the other two wildcards (*)

FindID("John", "Red", "Brown"); – should return 6, matched on “John” and “Brown” and one wildcard

FindID("Brian", "Grey", "Grey"); – should return 8, matched on three wildcard

The code below is complete and can be executed.

Does anyone know the best way of doing this?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TableScan
{
    class Program
    {
        public static TableClass _MyTable = new TableClass();

        public class TableRow
        {
            public int ID;
            public string Name;
            public string Hair;
            public string Eyes;

            public TableRow(int _ID, string _Name, string _Hair, string _Eyes)
            {
                ID = _ID;
                Name = _Name;
                Hair = _Hair;
                Eyes = _Eyes;
            }
        }

        public class TableClass
        {
            public List<TableRow> Table = new List<TableRow>();
        }

        static void Main(string[] args)
        {
            // ID       Name        Hair        Eyes
            // 1        John        Black       Brown
            // 2        Paul        Brown       Green
            // 3        Ringo       Blond       Blue
            // 4        George      Red         Blue
            // 5        John        *           *
            // 6        John        *           Brown
            // 7        *           Red         *
            // 8        *           *           *
            // 9        Paul        *           *

            CreateTable();

            ShowTable();

            FindID("John", "Black", "Brown");  // should return 1, complete match

            FindID("John", "Red", "Green");  // should return 5 (not 7), matched on "John" and the other two wildcards (*)

            FindID("John", "Red", "Brown");  // should return 6, matched on "John" and "Brown" and one wildcard

            FindID("Brian", "Grey", "Grey");  // should return 8, matched on three wildcard

            while (Console.ReadKey().Key == 0) { }
        }

        static int FindID(string _Name, string _Hair, string _Eyes)
        {
            // needs to be implemented

            return 0;
        }

        static void CreateTable()
        {
            _MyTable.Table.Add(new TableRow(1, "John", "Black", "Brown"));
            _MyTable.Table.Add(new TableRow(2, "Paul", "Brown", "Green"));
            _MyTable.Table.Add(new TableRow(3, "Ringo", "Blond", "Blue"));
            _MyTable.Table.Add(new TableRow(4, "George", "Red", "Blue"));
            _MyTable.Table.Add(new TableRow(5, "John", "*", "*"));
            _MyTable.Table.Add(new TableRow(6, "John", "*", "Brown"));
            _MyTable.Table.Add(new TableRow(7, "*", "Red", "*"));
            _MyTable.Table.Add(new TableRow(8, "*", "*", "*"));
            _MyTable.Table.Add(new TableRow(9, "Paul", "*", "*"));
        }

        static void ShowTable()
        {
            foreach(TableRow _TableRow in _MyTable.Table)
            {
                Console.WriteLine("{0} {1} {2} {3}", _TableRow.ID, _TableRow.Name, _TableRow.Hair, _TableRow.Eyes);
            }
        }
    }
}

Answer 1

ok pretty dead tonight, here’s a solution based on comment see http://ideone.com/rR46Ws

static bool match(TableRow row, string _Name, string _Hair, string _Eyes)
        {
                return (row.Name == _Name || row.Name == "*") && (row.Hair == _Hair || row.Hair == "*") && (row.Eyes == _Eyes || row.Eyes == "*");
        }

        static int score(TableRow row)
        {
                //can assume these already "match"
                var score = 0;
                score +=  row.Name == "*" ? 1000 : 2000; 
                score +=  row.Hair == "*" ? 100 : 200; 
                score +=  row.Eyes == "*" ? 10 : 20; 
                return score;
        }

        static int FindID(string _Name, string _Hair, string _Eyes)
        {

            var s = from row in _MyTable.Table
                        where match(row, _Name, _Hair, _Eyes)
                        orderby score(row) descending
                        select row;


            var match = s.FirstOrDefault();
            if(match != null) return match.ID;
            return -1; //i guess?
        }