Android Code Snippet [B4X][LOA] Fast range lookups based on binary search

Depends on ListOfArrays v1.01+

Works with numbers or strings. Make sure to sort the LOA based on the key column.

'Returns a sorted LOA containing all rows where the value in the specified column is within the given range (inclusive).
'The input LOA must be sorted by the specified column.
Private Sub FindRange(loa As ListOfArrays, Column As Object, StartRange As Object, EndRange As Object) As ListOfArrays
    Dim ix1 As Int = loa.BinarySearch(Column, StartRange)
    Dim ix2 As Int = loa.BinarySearch(Column, EndRange)
    If ix1 < 0 Then
        ix1 = -(ix1 + 1)
    Else
        Do While ix1 >= 0 And SafeCompare(StartRange, loa.GetValue(ix1, Column))
            ix1 = ix1 - 1
        Loop
        ix1 = ix1 + 1
    End If
    If ix2 < 0 Then
        ix2 = -(ix2 + 1) - 1
    Else
        Do While ix2 < loa.Size And SafeCompare(EndRange, loa.GetValue(ix2, Column))
            ix2 = ix2 + 1
        Loop
        ix2 = ix2 - 1
    End If
    ix1 = ix1 + loa.mFirstDataRowIndex
    ix2 = ix2 + loa.mFirstDataRowIndex
    Dim SubList As List = B4XCollections.CreateList(loa.mInternalArray.SubList(ix1, ix2 + 1))
    If loa.FirstRowIsHeader Then
        Return LOAUtils.WrapAddHeader(SubList, loa.Header)
    Else
        Return LOAUtils.WrapWithoutHeader(SubList)
    End If
End Sub

Private Sub SafeCompare (o1 As Object, o2 As Object) As Boolean
    If o1 Is Long Then
        Return o1.As(Long) = o2
    Else If o1 Is String Then
        Return o1.As(String) = o2
    Else
        Return o1.As(Double) = o2
    End If
End Sub

Usage example:

Dim data As ListOfArrays = LOAUtils.CreateEmpty(Array("Id", "Price"))
For i = 1 To 1000
    data.AddRow(Array("Item #" & NumberFormat2(i, 3), Rnd(1, 1000)))
Next
data.Sort("Price")
Dim r As ListOfArrays = FindRange(data, "Price", 50, 60)
Log(r.ToString(0))

Output:
Id Price (#rows=9, #cols=2)
-----------------------------
Item #648 50
Item #951 51
Item #347 53
Item #042 56
Item #263 56
Item #240 57
Item #311 58
Item #677 58
Item #086 60