Question

是否有一种简单的方法可以在列表中找到重复项，然后按外观数量对它们进行排序？此外，应删除重复项。

EG。你有这样的List<String>：

List<String> = new List<String>{"6","1","2","2","4","6","5","1","6","6","2"};

问题是，如何将此列表转换为 - ＆gt; “6”，“1”，“2”，“4”，“5”？

Answer 1

我认为最简单的方法是使用LINQ方法Distinct()：

var originalList = …;
vat withoutDuplicates = originalList.Distinct();

虽然您应该注意Distinct()的结果顺序明确没有记录。

Answer 2

使用Linq.Distinct()

List<String> list = new List<String>{"6","1","2","2","4","6","5","1","6","6","2"};
list = list.Distinct().ToList();

Answer 3

如果你真的希望从最常见到最少订购它们 - 不像你的例子那样 -

var ordered = list
    .GroupBy(i => i)
    .OrderByDescending(g => g.Count())
    .Select(g => g.Key);

应该实现这一点。

Answer 4

Using System.Linq;
// Assuming inputList was the original string list
List<String> deDuped = inputList.Distinct().ToList();

Answer 5

由于目前尚不清楚你的意思，这里有两种可能含义的解决方案：

获取按出现次数排序的唯一列表：

将列表分组并按Count()排序：

List<String> list = new List<String>{"6","1","2","2","4","6","5","1","6","6","2"};

var q = from s in list
group s by s into g
orderby g.Count() descending
select g.Key;

获取按列表中第一次出现的项目排序的唯一列表

已经有一些使用Distinct的建议，但是documentation并不保证它们按照它们在列表中出现的顺序出现（当前Enumerable实现恰好对它们进行排序这样，但对于其他供应商，它不能保证）：

<强>说明
结果序列是无序的。

为了保证订单，请添加OrderBy子句：
```
var q = list.Distinct().OrderBy(s => list.IndexOf(s));
```

Answer 6

还不是最干净的，但这提供了正确的结果。

var originalData = new List<string>{"6","1","2","2","4","6","5","1","6","6","2"};
var result = new List<string>();

foreach (var myString in originalData)
{
    if (!result.Exists(s => s == myString))
        result.Add(myString);
}

如何在列表中查找重复项并按外观数量对它们进行排序

6 个答案: