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Efficient method to find a value in a table "C #

I need to find a value in a "table" where the table can be an array or whatever. On paper, it looks like this (abbreviated and summarized):

Size      500     750    1000    1250   1500 (speed)
--------------------------------------------
6x5       0.1     0.5     0.55   0.58   0.8
6x4       0.01    0.1     0.4    0.5    0.9
8x5       0.5     0.9     1.1    1.5    2.0
10x5      1.2     1.5     2.0    2.7    3.0
12x6      2.6     3.0     4.4    5.1    7.0  (pressure)

I need to extract pressure somehow when I have variable size and speed.
I have put each line in a separate array right now, but I would like to avoid a bunch of if else, but I really don't know a better way. Thanks for the help.

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4 answers


Assuming your size and speed are always specific values ​​and do not fall between the values ​​given in your example (for example, no size 780

or 598

), the fastest way to perform a speed and size search is to have Dictionary<SizeAndSpeed, double>

, where SizeAndSpeed

is a class like this:

public class SizeAndSpeed : IEquatable<SizeAndSpeed>
{
    public string Size { get; set; }
    public int Speed { get; set; }
    public bool Equals(SizeAndSpeed other)
    {
        return Size == other.Size && Speed == other.Speed;
    }
}


I suppose it Size

can be string

, but of course a more complex object can be used.

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if the size is unique, make it a key to the dictionary and then you can use it to get other items ...



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At the top of my head, you can use DataTable.

Size      Speed     Pressure
--------------------------------------------
6x5       500       0.1
6x5       750       0.5
6x5       1000      0.55
6x5       1250      0.58
6x5       1500      0.8
6x4       500       0.01
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Create a structure to keep the size and speed of the pair:

public struct SizeSpeedKey
{
public string Size;
public int Speed;

public SizeSpeedKey(string size, int speed)
{
  Size = size;
  Speed = speed;
}
}

Then this would be the search code:

using System;
using System.Collections.Generic;

namespace LookupTable
{
  internal class Program
  {
    private static readonly Dictionary<SizeSpeedKey, double> lookupTable =
      new Dictionary<SizeSpeedKey, double>
      {
        {new SizeSpeedKey("6x5", 500), 0.1},
        {new SizeSpeedKey("6x5", 750), 0.5},
        {new SizeSpeedKey("6x4", 500), 0.01},
        {new SizeSpeedKey("6x4", 750), 0.1},
        {new SizeSpeedKey("8x5", 500), 0.5},
        {new SizeSpeedKey("8x5", 750), 0.9},
      };

    private static void Main(string[] args)
    {
      // these will of course need to be read from the user
      var size = "6x4";
      var speed = 500;

      Console.WriteLine("For size = {0} and speed = {1}, the pressure will be {2}", size, speed, lookupTable[new SizeSpeedKey(size, speed)]);
      Console.ReadLine();
    }
  }
}
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