arrays - 查找、计数和索引数组中的重复项

Question

我有一个数组，它有一些重复的值。
我必须计算每个重复项的数量及其索引。
打印如:

Index of b: 1
Index of b: 4
Index of c: 2
Index of c: 3
Index of c: 5
Index of e: 7
Index of e: 8

Total duplicate b: 2
Total duplicate c: 3
Total duplicate e: 2

    

在我的代码中，我只能找到重复的值。

Dim list As New List(Of String) From {"a", "b", "c", "c", "b", "c", "d", "e", "e"}
Dim duplicates = list.GroupBy(Function(x) x).Where(Function(x) x.Count > 1).Select(Function(x) x.Key)

For Each i As String In list.ToArray
    If duplicates.Contains(i) Then
        Debug.WriteLine("Duplicate Element: " & i & "Index:  " & list.IndexOf(i))
    End If
Next

这给出了输出:

Duplicate Element: bIndex:  1
Duplicate Element: cIndex:  2
Duplicate Element: cIndex:  2
Duplicate Element: bIndex:  1
Duplicate Element: cIndex:  2
Duplicate Element: eIndex:  7
Duplicate Element: eIndex:  7

Answer 1

一种方法

    Dim list As New List(Of String) From {"a", "e", "e", "b", "c", "c", "b", "c", "d", "e"}
    Dim duplicates As IEnumerable(Of String) = list.Distinct
    duplicates = From s In duplicates
                  Where list.FindAll(Function(l) l = s).Count > 1
                  Select s

    For Each s As String In duplicates
        Dim ct As Integer = (From l In list Where l = s Select l).Count
        Debug.WriteLine(s)
        Debug.WriteLine("count:{0}", ct)
        Dim idx As IEnumerable(Of Integer)
        idx = From n In Enumerable.Range(0, list.Count)
              Where list(n) = s
              Select n Take ct

        Debug.WriteLine("Indexes")
        For Each n As Integer In idx
            Debug.Write(n.ToString)
            Debug.Write(" ")
        Next
        Debug.WriteLine("")
    Next

输出

e
count:3
Indexes
1 2 9 
b
count:2
Indexes
3 6 
c
count:3
Indexes
4 5 7