Question

我有一份清单。

public List<Objects> obj;

此列表中的对象需要添加到其他列表中。

public List<Objects> objGroup1, objGroup2, objGroup3, objGroup4;

我现在通过这样做来分配它们。

void AssignToGroups()
{
    for(int i = 0; i < obj.Count ; i++)
    {
//Need the first 4 for group 1 next 4 for group 2 and so on...

        if(i < 4)
        {
            objGroup1.Add(obj[i]);
        }

        else if(i >= 4 && i < 8)
        {
            objGroup2.Add(obj[i]);
        }

        else if (i >= 8 && i < 12)
        {
            objGroup3.Add(obj[i]);
        }

        else if (i >= 12 && i < 16)
        {
            objGroup4.Add(obj[i]);
        }
    }
}

我正计划进行扩展，现在我的分组对象的方法将用无穷无尽的if和else语句填充我的屏幕。

需要为每个组分配4个对象。组中的对象按其排列顺序获取它们。例如group1得到obj 1-4。第2组得到对象5-8等等......

有没有人有更好的方法来分组这样的对象？

Answer 1

您可以使用Skip和Take方法。

您需要using System.Linq;：

objGroup1 = obj.Take(4).ToList();           //edited: use ToList() to keep the list format
objGroup2 = obj.Skip(4).Take(4).ToList();
objGroup3 = obj.Skip(8).Take(4).ToList();    
objGroup4 = obj.Skip(12).Take(4).ToList();
objGroup5 = obj.Skip(16).Take(4).ToList();

让我知道它是否有效，因为我现在无法测试它，除了语法。

您还可以在obj之前对Take()进行分组，例如

var orderedobj = obj.OrderBy(i => "some order criteria").ToList();
objGroup1 = orderedobj.Take(4);
...

我在How to get first N elements of a list in C#?上引用了我的答案。

编辑：

如果您以某种方式不想使用Linq，您也可以使用GetRange

objGroup1 = obj.GetRange(0, 4);
objGroup2 = obj.GetRange(3, 4);     //since GetRange(index, count) has index starting from 0 instead of 1
objGroup3 = obj.GetRange(7, 4);     //count stays the same since we always want 4 elements
objGroup4 = obj.GetRange(11, 4);
objGroup5 = obj.GetRange(15, 4);

Answer 2

使用Keyur的优秀答案，您可以创建一种方法，根据任何源列表为您创建具有可配置组大小的组：

private static List<List<object>> AssignToGroups(List<object> source, int groupSize)
{
    var groups = new List<List<object>>();

    if (source == null || groupSize < 1) return groups;

    for (int i = 0; i < source.Count / groupSize; i++)
    {
        groups.Add(source.Skip(groupSize * i).Take(groupSize).ToList());
    }

    return groups;
}

<强>用法

private static void Main()
{
    var mainList = new List<object>
    {
        "one", "two", "three", "four","five",
        "six","seven","eight","nine","ten",
        "eleven", "twelve", "thirteen", "fourteen","fifteen",
        "sixteen","seventeen","eightteen","nineteen","twenty",
        "twentyone", "twentytwo", "twentythree", "twentyfour","twentyfive",
        "twentysix","twentyseven","twentyeight","twentynine","thirty",
        "thirtyone", "thirtytwo", "thirtythree", "thirtyfour","thirtyfive",
        "thirtysix","thirtyseven","thirtyeight","thirtynine","forty",
    };

    var groups = AssignToGroups(mainList, 4);

    for (var i = 0; i < groups.Count; i++)
    {
        Console.WriteLine($"Group #{i + 1}: {string.Join(", ", groups[i])}");
    }

    Console.WriteLine("\nDone!\nPress any key to exit...");
    Console.ReadKey();
}

<强>输出

将另一个列表中的对象分配给另一组列表

2 个答案: