我可以在IOrderedEnumerable列表中添加where子句吗？

Question

I have a list of arrays. Each array consists of a score and a difficulty. Read in from a text file.

This is how I get the data and order it by the score in descending order.

// load highscores
public void LoadScores()
{
    // loop through each line in the file
    while ((line = file.ReadLine()) != null)
    {
        // seperate the score from the difficulty
        lineData = line.Split(',');

        // add each line to the list
        list.Add(lineData);
    }

    // order the list by descending order
    IOrderedEnumerable<String[]> scoresDesc = list.OrderByDescending(ld => lineData[0]);

}

Is it possible to add the a clause to the IOrderedEnumerable so that it orders by the score in descending order where the difficulty is 1 ?

Answer 1

Assuming the "difficulty" is the second item in the array:

 IEnumerable<String[]> scoresDesc =
     list.OrderByDescending(ld => lineData[0])
         .Where(ld => lineData[1] == 1);

You can sort it afterwards, but Where returns an IEnumerable<T> , not an IOrderedEnumerable<T> , so if you need it to be an IOrderedEnumerable<T> then it's cleaner (and faster) to filter the list first:

 IOrderedEnumerable<String[]> scoresDesc =
     list.Where(ld => lineData[1] == 1)
         .OrderByDescending(ld => lineData[0]);

(this is where var eases some pain, since you aren't bound to the return type)

Answer 2

如果要针对困难1进行过滤，则可以使用.Where()扩展方法，如果要按多个字段进行排序，则可以使用.ThenBy()扩展方法。

Answer 3

首先过滤，然后订购：

list.Where(x => x.difficulty == 1).OrderByDescending(ld => lineData[0]);