使用 LINQ 计算 Lists int C# 字典的平均值

Question

I have a dictionary containing n pair key/value and I want to get the total average of the first two values in each list in my dictionary. Here is an example:

    private Dictionary<int, List<float>> _myValues = new Dictionary<int, List<float>>
    {
        {1, new List<float>{0.1f, 0.2f, 0.3f},
        {2, new List<float>{0.4f, 0.5f, 0.6f, 0.7f},
        {3, new List<float>{0.8f}
    };

For this example, I want the average of these values ( 0.1f , 0.2f , 0.4f , 0.5f , 0.8f ).

I see that I can do this using for/foreach loop, but I wonder if it's possible to get that average using a simple LINQ query.

Answer 1

For this example, I want the average of these values (0.1f, 0.2f, 0.4f, 0.5f, 0.8f).

Dictionary<int, List<float>> _myValues = new Dictionary<int, List<float>>
{
    {1, new List<float>{0.1f, 0.2f, 0.3f}},
    {2, new List<float>{0.4f, 0.5f, 0.6f, 0.7f}},
    {3, new List<float>{0.8f}}
};

var result = _myValues.Values.SelectMany(z => z.Take(2)).Average();

Values will get the values from the Dictionary (ie ignore the Keys since they don't impact the result). Take(2) will get the first two entries from each list. SelectMany will effectively concatenate all of those two entries into a single projection. And Average will average them.