将数组列出为单独的数组

Question

I have a constructor which uses a List parameter. Inside that list I have three items which are 3 integer arrays.

public HistogramLogic(List<Tuple<int[], int[], int[]>> separateRGB)

Now I want to initialize three new integer arrays with the arrays inside that list. But when I try this code, the index of my new arrays stay 0.

for (int i = 0; i < histogramXValues.Length; i++)
{
     rArray = separateRGB.Select(obj => obj.Item1[i]).ToArray();
     gArray = separateRGB.Select(obj => obj.Item2[i]).ToArray();
     bArray = separateRGB.Select(obj => obj.Item3[i]).ToArray();
}

Anyone got any suggestions on how to fix this?

Answer 1

你可以从touple获得物品

rArray = separateRGB.Select(obj => obj.Item1);

Answer 2

Bear in mind, if you have a list of N tuples, you start with 3 x N arrays. Sounds like you want them combined into 3 arrays, each containing all of the elements throughout the list. Which you can do with SelectMany .

rArray = separateRGB.SelectMany(obj => obj.Item1).ToArray();
gArray = separateRGB.SelectMany(obj => obj.Item2).ToArray();
bArray = separateRGB.SelectMany(obj => obj.Item3).ToArray();

Full example:

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

public class Program
{
    static public void HistogramLogic(List<Tuple<int[], int[], int[]>> separateRGB)
    {
        var rArray = separateRGB.SelectMany(obj => obj.Item1).ToArray();
        var gArray = separateRGB.SelectMany(obj => obj.Item2).ToArray();
        var bArray = separateRGB.SelectMany(obj => obj.Item3).ToArray();

        Console.WriteLine("rArray = {{{0}}}", string.Join(",", rArray));
        Console.WriteLine("gArray = {{{0}}}", string.Join(",", gArray));
        Console.WriteLine("bArray = {{{0}}}", string.Join(",", bArray));
    }

    public static void Main()
    {
        var mockData = new List<Tuple<int[], int[], int[]>>
        {
            Tuple.Create(new[] {11,12,13}, new[] {14,15,16}, new[] {17,18,19}),
            Tuple.Create(new[] {21,22,23}, new[] {24,25,26}, new[] {27,28,29}),
            Tuple.Create(new[] {31,32,33}, new[] {34,35,36}, new[] {37,38,39})
        };

        HistogramLogic(mockData);
    }
}

Output:

rArray = {11,12,13,21,22,23,31,32,33}
gArray = {14,15,16,24,25,26,34,35,36}
bArray = {17,18,19,27,28,29,37,38,39}

Click here for code on DotNetFiddle

Answer 3

Like they sad in comments you did reassign local member in each loop. You could use something like this.

public HistogramLogic(List<Tuple<int[], int[], int[]>> separateRGB)
{
    List<int> rList = new List<int>();
    List<int> gList = new List<int>();
    List<int> bList = new List<int>();

    separateRGB.ForEach((Tuple<int[], int[], int[]> tpl) =>
    {
        rList.AddRange(tpl.Item1);
        gList.AddRange(tpl.Item1);
        bList.AddRange(tpl.Item1);

    });

    rArray = rList.ToArray();
    gArray = gList.ToArray();
    bArray = bList.ToArray();

}

If you wish to not use temp List object you should know final count of elements in tuple, create local array member to desired size. and fill it. List are more suitable for adding and expanding elements. Maybe you could use one Linq Statement but if I understand goal is to get one int[] array per color. If you take

separateRGB.AsQueryable().Select(m => m.Item1).ToArray();

as a result you get int[][] result instead of simple int array;