Question

        int numPics = 3; //Populated from a query
        string[] picID = new string[numPics];
        //pictureTable is constructed so that it correlates to pictureTable[column][row]
        string[][] pictureTable = null; //assume the table has data
        for (int i = 0; i < numPics; i++)
        {
            //LINQ query doesn't work. Returns an IEnumerable<string> instead of a string.
            picID[i] = pictureTable.Where(p => p[0].Equals("ID")).Select(p => p[i]);
        }

我是LINQ的新手，但我一直在寻找并且没有找到答案。我希望能够使用LINQ检查pictureTable中每列的第一个字符串，看它是否与字符串匹配。然后，我想获取该列并从0到i的每一行中提取数据。我知道我可以通过更改列并保持行相同来使用for循环，但我想使用LINQ来实现相同的结果。

此外，如果有可能摆脱第一个for循环并获得相同的结果，我也会对此感兴趣。

编辑：让我们说我们有一个包含以下数据的表，请记住一切都是字符串。

Column Name    [ID]  [Name]  [Age]
Row 1           [1]   [Jim]   [25]   
Row 2           [2]   [Bob]   [30]
Row 3           [3]   [Joe]   [35]

我希望能够查询列名，然后能够通过索引或查询行的数据从中获取数据。我将举一个使用for循环来实现我想要的例子。

        string[][] table = new string[][] { 
                              new string[] { "ID", "Name", "Age" }, 
                              new string[] { "1",  "Jim",  "25" },
                              new string[] { "2",  "Bob",  "30" },
                              new string[] { "3",  "Joe",  "35" }};

        string[] resultRow = new string[table.GetLength(1)];
        for (int i = 0; i < table.GetLength(0); i++)
        {
            if (table[i][0] == "Name") //Given this in a LINQ Query
            {
                Console.WriteLine("Column Name = {0}\n", table[i][0]);
                for (int j = 1; j < table.GetLength(1); j++) //starts at 1
                {
                    resultRow[i] = table[i][j]; //This is what I want to happen.
                }
                break; //exit outer loop
            }
        }
        //Output:
        //Column Name = Name

Answer 1

您是否只想将字符串连接在一起？如果是这样，你可以这样做：

picID[i] = string.Concat(pictureTable.Where(p => p[0].Equals("ID")).Select(p => p[i]));

Answer 2

我认为这会给你相当于你在resultRow数组中寻找的东西

string[][] table = new string[][] { 
    new string[] { "ID", "Name", "Age" }, 
    new string[] { "1", "Jim", "25" },
    new string[] { "2", "Bob", "30" },
    new string[] { "3", "Joe", "35" }
};

//get index of column to look at
string columnName = "Name";
var columnIndex = Array.IndexOf(table[0], columnName, 0);

// skip the title row, and then skip columns until you get to the proper index and get its value
var results = table.Skip(1).Select(row => row.Skip(columnIndex).FirstOrDefault());

foreach (var result in results)
{
    Console.WriteLine(result);
}

另一个需要注意的是SelectMany，因为您可以使用它将多个列表展平为单个列表。

查询锯齿状数组中所有列中的第一个元素

2 个答案: