问题

这是我要翻译的部分：

"Hi I want to order by two columns using LINQ

This is the LINQ that I have:

List<FromTextFile> sortedList = ColumnsSwapped
    .OrderBy(o => o.Column1)
    .ThenBy(o => o.Column2)
    .ToList();

This is the result that I am getting:

    Column1; Column2
    QA7878729D; D9278787AQ
    QA7878736A; A6378787AQ
    QA7878751B; B1578787AQ
    QA7878834C; C4388787AQ
    QB7878726D; D6278787BQ

This is the result that I want:

    Column1; Column2
    QA7878736A; A6378787AQ
    QA7878751B; B1578787AQ
    QA7878834C; C4388787AQ
    QA7878729D; D9278787AQ
    QB7878726D; D6278787BQ

Is there something wrong with my LINQ? Am I not using .ThenBy() correctly?

I want to order Column1 QA > QB and for Column2 after ordering the Column1, it sorts from A > B.

    QA-A
    QA-B
    QA-C
    QA-D
    QB-D
```"

<details>
<summary>英文:</summary>

Hi I want to order by two columns using LINQ

This is the LINQ that I have:

```csharp
List&lt;FromTextFile&gt; sortedList = ColumnsSwapped
    .OrderBy(o =&gt; o.Column1)
    .ThenBy(o =&gt; o.Column2)
    .ToList();

This is the result that I am getting:

    Column1; Column2
    QA7878729D; D9278787AQ
    QA7878736A; A6378787AQ
    QA7878751B; B1578787AQ
    QA7878834C; C4388787AQ
    QB7878726D; D6278787BQ

This is the result that I want:

    Column1; Column2
    QA7878736A; A6378787AQ
    QA7878751B; B1578787AQ
    QA7878834C; C4388787AQ
    QA7878729D; D9278787AQ
    QB7878726D; D6278787BQ

Is there something wrong with my LINQ? Am I not using .ThenBy() correctly?

I want to order Column1 QA > QB and for Column2 after ordering the Column1, it sorts from A > B.

    QA-A
    QA-B
    QA-C
    QA-D
    QB-D

答案1

得分: 1

根据您的期望结果，您应该按以下方式排序：

1. Column1 的前两个字符以实现 QA > QB

2. Column2 的第一个字符以实现 A > B

（可选）如果您希望按顺序进一步排序 Column1 和 Column2：

3. Column1

4. Column2

List<FromTextFile> SortedList = ColumnsSwapped
    .OrderBy(o => o.Column1.Substring(0, 2))
    .ThenBy(o => o.Column2.Substring(0, 1))
    .ThenBy(o => o.Column1)
    .ThenBy(o => o.Column2)
    .ToList();

List<FromTextFile> SortedList = ColumnsSwapped
    .OrderBy(o => o.Column1.Substring(0, 2))
    .ThenBy(o => o.Column2.Substring(0, 1))
    .ThenBy(o => o.Column1)
    .ThenBy(o => o.Column2)
    .ToList();

答案2

得分: 0

看起来你只想按Column1的前两个字符和Column2的第一个字符进行排序。如果是这样的话，你只需要将你的 Linq 改成：

List<FromTextFile> SortedList = ColumnsSwapped.OrderBy(o => o.Column1.Substring(0, 2)).ThenBy(o => o.Column2.Substring(0, 1)).ToList();

这样会忽略掉最后的字符，这意味着你会在Column1中得到“重复”的结果，这将导致ThenBy按Column2的第一个字符进行排序。

另一种语法（完全相同）：

List<FromTextFile> SortedList = ColumnsSwapped.OrderBy(o => o.Column1[..2]).ThenBy(o => o.Column2[0]).ToList();

List<FromTextFile> SortedList = ColumnsSwapped.OrderBy(o => o.Column1.Substring(0, 2)).ThenBy(o => o.Column2.Substring(0, 1)).ToList();

List<FromTextFile> SortedList = ColumnsSwapped.OrderBy(o => o.Column1[..2]).ThenBy(o => o.Column2[0]).ToList();