Adding rows based on current and next row

Question

I got some excellent help on multiplying rows based on start and end date in this
thread, resulting in the query below. It helps me follow Vehicle activity and Vehicle allocation of our vehicles day by day. Now I would like to add another feature to the query, if it is possible.
The problem is that in our database, only actual tasks are registered, which means that the time when the vehicle is between tasks is not showing. I could of course calculate total available time per vehicle and month, but that would not tell me where the
vehicles are waiting, when during the day, etc.
So I would like to insert rows for when the vehicles are standing still, and the logic would be something like this:
If vehicle number on current row equals vehicle number on the next row and End (date/time) of current row < Start (date/time) of next row, insert row after current row. Set Start=End of current row and End=Start of next row. Set From=To
of current row and To=To of current row. Set Vehicle activity to "Not active". Finaly copy all other fields from current row.
Is this possible to achieve in Power Query?
Brgds,
Caj
let
    Source = Sql.Databases("sql10"),
    SLM = Source{[Name="SLM"]}[Data],
    dbo_V_LKPI = SLM{[Schema="dbo",Item="V_LKPI"]}[Data],
    RenamedColumns = Table.RenameColumns(dbo_V_LKPI,{{"ActualDeparture", "Start"}, {"ActualArrival", "End"}}),
     Records = Table.ToRecords(V_LocoKPI),
      DateTime.IsSameDay = (x, y) => Date.Year(x) = Date.Year(y) and Date.Month(x) = Date.Month(y) and Date.Day(x) = Date.Day(y),
      Expand = (x) => List.Generate(
          () => Record.Combine({x, [End=Date.EndOfDay(x[Start])]}),
          (record) => record[Start] <= x[End],
          (record) => let
              NextStart = Date.StartOfDay(Date.AddDays(record[Start], 1)),
              NextEnd = Date.EndOfDay(NextStart),
              ThisEnd = List.Min({NextEnd, x[End]})
          in
              Record.Combine({record, [Start=NextStart, End=ThisEnd]})),
      Transformed = List.Transform(Records, each if DateTime.IsSameDay([Start], [End]) then {_} else Expand(_)),
      Combined = List.Combine(Transformed),
      Result = Table.FromRecords(Combined)
  in
      Result
Csten

Answer 1

Here's some sample code. Again, we use List.Generate to build either a record or a list of records and then use List.Combine to bring the results back together before converting them to a table.
let
    CombineTwoRows = (x, y) =>
        let
            combine = x[Vehicle] = y[Vehicle] and x[End] < y[Start],
            added = Record.Combine({x, [Start=x[End], End=y[Start], Active=false]}),
            result = if combine then {added, y} else {y}
        in result,
    GenerateStandingRows = (table, combine) =>
        let
            Handle = (x, y) => {x, y},
            buffered = Table.Buffer(table),
            n = Table.RowCount(buffered),
            windows = List.Generate(
                () => {1, {buffered{0}}},
                (x) => x{0} <= n,
                (x) => {x{0} + 1, if x{0} < n then combine(buffered{x{0}-1}, buffered{x{0}}) else {buffered{x{0}}}},
                (x) => x{1})
        in
            windows,
    InsertInactivity = (table) => Table.FromRecords(List.Combine(GenerateStandingRows(table, CombineTwoRows))),
    TestData = Table.FromRows({
        {1, #datetime(2014, 2, 23, 13, 0, 0), #datetime(2014, 2, 23, 13, 10, 0), true},
        {1, #datetime(2014, 2, 23, 13, 20, 0), #datetime(2014, 2, 23, 13, 30, 0), true},
        {2, #datetime(2014, 2, 23, 13, 20, 0), #datetime(2014, 2, 23, 14, 0, 0), true},
        {2, #datetime(2014, 2, 23, 14, 20, 0), #datetime(2014, 2, 23, 14, 40, 0), true},
        {2, #datetime(2014, 2, 23, 16, 0, 0), #datetime(2014, 2, 23, 17, 0, 0), true},
        {2, #datetime(2014, 2, 24, 2, 0, 0), #datetime(2014, 2, 24, 3, 0, 0), true},
        {3, #datetime(2014, 2, 24, 1, 0, 0), #datetime(2014, 2, 24, 8, 0, 0), true},
        {3, #datetime(2014, 2, 24, 9, 0, 0), #datetime(2014, 2, 24, 10, 0, 0), true}
        }, {"Vehicle", "Start", "End", "Active"})
in
    InsertInactivity(TestData)