Question

有一个返回2D数组的方法，此方法从LINQ查询查询字典并尝试在2D数组中存储键和值。

但我无法做到这一点

public string[][] GetRecordFields(string selectedRecord)
    {

        var recordFields = (from record in _recordMasterList
                            where record.Item1 == selectedRecord
                            select new 
                            {
                                record.Item2.Keys,
                                record.Item2.Values
                            }).ToArray();
      return recordFields;       
  }

但它失败了，有什么办法吗？

编辑： _recordMasterList

的类型

List<Tuple<string, Dictionary<string, string>>> _recordMasterList;

Answer 1

在查询中创建一个字符串数组而不是一个对象，然后ToArray将返回一个数组数组：

public string[][] GetRecordFields(string selectedRecord) {
  return (
    from record in _recordMasterList
    where record.Item1 == selectedRecord
    select new string[] {
      record.Item2.Keys,
      record.Item2.Values
    }
  ).ToArray();
}

Answer 2

在select中，您需要创建一个字符串数组（new []）。在您的示例中，您创建了一个新的anonymous type。

public string[][] GetRecordFields(string selectedRecord)
{
    string[][] recordFields = (from record in _recordMasterList
                        where record.Key == selectedRecord
                        select new []
                        {
                            record.Key,
                            record.Value
                        }).ToArray();

    return recordFields;
}

（我稍微更改了代码以处理类型_recordMasterList的{{1}}。此外，在这样的代码中，我发现明确声明我的变量类型更清楚，而不是依赖于{ {3}}。也就是说，对于数组，我更喜欢使用implicit typing - Dictionary<string, string>而不是new []。）

Answer 3

不是单行LINQ魔术，但在这里是：

/// <summary>
/// Converts dictionary to 2d string array
/// </summary>
/// <param name="Dictionary">Dictionary to be converted</param>
/// <returns>2D string Array</returns>
private string[,] ConvertDictionaryTo2dStringArray(Dictionary<string, string> Dictionary)
{
    string[,] stringArray2d = new string[2, Dictionary.Count];
    int i = 0;

    foreach (KeyValuePair<string, string> item in Dictionary)
    {
        stringArray2d[0, i] = item.Key;
        stringArray2d[1, i] = item.Value;
        i++;
    }

    return stringArray2d;
}

Answer 4

你的问题仍然有点令人困惑。这是你正在寻找的行为吗？

（我知道这个答案可以进行很多优化，但它最容易找出你想要的东西。）

public string[,] GetRecordFields(string selectedRecord)
{
    //List<Tuple<string, Dictionary<string, string>>> _recordMasterList;

    List<Dictionary<string, string>> selectedRecords
        = (from record in _recordMasterList
            where record.Item1 == selectedRecord
            select record.Item2)
            .ToList();

    int totalNumberOfRecords = 0;

    foreach(Dictionary<string, string> d in selectedRecords)
    {
        totalNumberOfRecords += d.Count();
    }

    string[,] result = new string[2, totalNumberOfRecords];

    int i = 0;
    foreach(Dictionary<string, string> d in selectedRecords)
    {
        foreach(KeyValuePair<string, string> kvp in d)
        {
            result[0,i] = kvp.Key;
            result[1,i] = kvp.Value;
            ii++;
        }
    }

    return result;
}

Answer 5

具有相反尺寸的更通用的版本：

private object[,] Dictionary2Array(Dictionary<object, object> dic)
{
    object[,] arr = new object[dic.Count, 2];
    int i = 0;

    foreach (KeyValuePair<object, object> item in dic)
    {
        arr[i, 0] = item.Key;
        arr[i, 1] = item.Value;
        i++;
    }

    return arr;
}

LINQ字典到锯齿状数组？

5 个答案: