List Sorting conundrum (try at your peril)

Ok, I have been attempting this problem for 2 solid weeks now and have to admit it's driving me insane.

Here is the data:

Code:

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  RowText AlloIndex  PosIndex    FromTime            ToTime        OverLap
    test1      0          0    21/06/2022 14:42    22/06/2022 2:43    0
    test2      0          0    21/06/2022 14:42    22/06/2022 2:43    1
    test3      0          0    22/06/2022 2:42    22/06/2022 14:43    0
    test4      0          0    22/06/2022 14:42    23/06/2022 2:43    0
    test5      5          5    21/06/2022 19:42    22/06/2022 7:43    0
    test6      6          6    21/06/2022 16:42    22/06/2022 4:43    0
    test7      7          7    21/06/2022 15:42    22/06/2022 3:43    0
    test8      7          7    21/06/2022 19:42    22/06/2022 7:43    1
    test9      8          8    21/06/2022 21:42    22/06/2022 9:43    0
    test10    8          8    21/06/2022 22:42    22/06/2022 10:43    1
    test11    9          9    22/06/2022 0:42    22/06/2022 12:43    0
    test12    9          9    21/06/2022 15:42    22/06/2022 3:43    1
    test13    9          9    22/06/2022 12:42    23/06/2022 12:43    1
    test14    9          9    22/06/2022 10:42    23/06/2022 10:43    1
    test15    10          10    21/06/2022 20:42    22/06/2022 8:43    0
    test16    10          10    22/06/2022 1:42    22/06/2022 13:43    1

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What I am attempting to do is, if there is a time overlap in the same **AlloIndex** group, increase the **PosIndex** of the overlaps by 1 (those identified as an overlap are those greater in time in the same **AlloInndex** group that overlap. I have already highlighted these by the **Overlap** column).

However, this is the tricky part, if an overlap increases the **PosIndex** by 1, all other rows with **PosIndex** values greater than the overlap **PosIndex** are also increased by 1. Example: **PosIndex** 0 has an overlap, so all **PosIndex** greater than 0 also have to increase by 1, in a sense moving them down the rank. **PosIdex** 9, in particular, is very tricky, because you have 4 entries, and 3 overlaps. So you have to increase the **PosIndex** of each overlapped entry by 1 (leaving the 1st entry in the group alone), but also any **PosIndex** greater also needs to increase by 1. Hope this makes sense.

I have tried **FOR LOOPS**, **LINQ**, and **lambda** to no avail...

This is the closest I have come to solving this, but it doesn't work when there are more than 2 overlaps in the same **AlloIndex** Group.

Code:

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For Each bar In lst     
   
        If prevFromDT < bar.ToTime
          And prevToDT > bar.FromTime
          And prevIndex = bar.PosIndex Then
   
            bar.overLap = True
   
        End If
   
    next
   
        For Each tsk In lst
   
            If tsk.overLap Then
   
                For Each tsk1 In lst
   
                    If tsk1.PosIndex > tsk.PosIndex Then
                        tsk1.PosIndex += 1
   
                    Next
   
            End If
   
        Next
   
        For Each tsk In lst
   
            If tsk.overLap Then
   
                tsk.PosIndex += 1
   
            End If
   
        Next

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The resulting data should look like this:

Code:

---

RowText        AlloIndex        PosIndex        FromTime              ToTime            OverLap
    test1          0                  0          21/06/2022 14:42        22/06/2022 2:43          0
    test2          0                  1          21/06/2022 14:42        22/06/2022 2:43          1
    test3          0                  0          22/06/2022 2:42        22/06/2022 14:43  0
    test4          0                  0          22/06/2022 14:42        23/06/2022 2:43          0
    test5          5                  6          21/06/2022 19:42        22/06/2022 7:43          0
    test6          6                  7          21/06/2022 16:42        22/06/2022 4:43          0
    test7          7                  8          21/06/2022 15:42        22/06/2022 3:43          0
    test8          7                  9          21/06/2022 19:42        22/06/2022 7:43          1
    test9          8                  10          21/06/2022 21:42        22/06/2022 9:43          0
    test10          8                  11          21/06/2022 22:42        22/06/2022 10:43  1
    test11          9                  12          22/06/2022 0:42        22/06/2022 12:43  0
    test12          9                  13          21/06/2022 15:42        22/06/2022 3:43          1
    test13          9                  14          22/06/2022 12:42        23/06/2022 12:43  1
    test14          9                  15          22/06/2022 10:42        23/06/2022 10:43  1
    test15          10              16          21/06/2022 20:42        22/06/2022 8:43          0
    test16          10              17          22/06/2022 1:42        22/06/2022 13:43  1

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I think i've solved it. Here is the code. Its a bit messy, but it works.

Code:

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    Private Sub addBedOverLapIndex()
   
            Dim i As Integer           
            Dim first As Boolean = True
   
            For Each bar In lstBars
   
                If (From x In lstBars Where x.FromTime < bar.ToTime And x.ToTime > bar.FromTime And x.PosIndex = bar.PosIndex And x.BookingUID <> bar.BookingUID).Any Then bar.overLap = True
                If bar.overLap Then
                    Dim test = From x In lstBars Where x.AllocationIndex = bar.AllocationIndex And bar.overLap = True And x.overLap = True
                    If test.Count > 1 Then
                        first = True
                        i = 1
                        For Each all In test
                            If Not first Then
                                all.BedOverLapIndex = i
                                i += 1
                            End If
                            first = False
                        Next
                    End If
                End If
           
   
            Next
   
        End Sub
   
   
   
        Public Sub sortbars()
   
            Dim j As Integer = 0
            Dim first As Boolean = True
   
            addBedOverLapIndex()
            Dim RemoveFirstOverlap = lstBars.Where(Function(ol1) ol1.overLap = True).GroupBy(Function(x) x.PosIndex, Function(key, g) g.OrderBy(Function(e) e.PosIndex).FirstOrDefault).ToList()
   
            For Each tst In RemoveFirstOverlap
                tst.overLap = False
            Next
   
            lstBars = (From x In lstBars Select x Order By x.AllocationIndex, x.BedOverLapIndex).ToList
   
   
            For Each s In lstBars
   
                If s.overLap Then j += 1
   
                If Not first Then s.PosIndex += j
   
                first = False
   
            Next

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