Power Query: Expression.Error: There weren't enough elements in the enumeration to complete the operation. (LIST)

Question

What I am trying to achieve is to obtain "matches/pairs" from two tables. One (source 1)is data.table with Date/Time and Pressure value columns and the other (source 2) is like Date/Time and Info value Columns. Second table has so called "pairs", start and stop in certain time. I want to get exact matches when is found in source 1 or approximate match when is not exact as in source 1 (seconds can be a problem).

Lets say you are matching/lookup two tables, give me everything that falls between for instance 15.01.2022 06:00:00 and 15.01.2022 09:15:29.

Where I have a problem is more likely exact match and seconds. It is skipping or cant find any pair if the seconds are not matching. So my question is how to make if not seconds then lookup for next availablee match, can be a minute too as long as they are in the given range (start stop instances). That is a reason I am getting this Expression error. Or is there a way to skip that error and proceed with Query??

Link to download the data:

https://docs.google.com/spreadsheets/d/1Jv5j7htAaEFktN0ntwOZCV9jesF43tEP/edit?usp=sharing&ouid=101738555398870704584&rtpof=true&sd=true

On the code below is what I am trying to do:

    let

//Be sure to change the table names in the Source= and Source2= lines to be the actual table names from your workbook
    Source = Excel.CurrentWorkbook(){[Name="Parameters"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date/Time", type datetime}, {"P7 [mbar]", Int64.Type}}),
       
//get start/stop times table
    Source2 = Excel.CurrentWorkbook(){[Name="Log_Original"]}[Content],
    typeIt = Table.TransformColumnTypes(Source2, {"Date/Time", type datetime}),
    #"Filtered Rows" = Table.SelectRows(typeIt, each ([#"Date/Time"] <> null)),
    #"Added Index" = Table.AddIndexColumn(#"Filtered Rows", "Index", 0, 1),

#"Added Custom" = Table.AddColumn(#"Added Index", "NextLineStart", each if Text.Contains([Info],"start", Comparer.OrdinalIgnoreCase) = true 
                and Text.Contains(#"Added Index"[Info]{[Index]+1},"start",Comparer.OrdinalIgnoreCase) = true 
            then "delete" 
            else null),
    #"Filtered Rows1" = Table.SelectRows(#"Added Custom", each ([NextLineStart] = null)),
    #"Removed Columns1" = Table.RemoveColumns(#"Filtered Rows1",{"Index", "NextLineStart"}),

//create a list of all the relevant start/stop times
     filterTimes = List.Combine(
                        List.Generate(
                            ()=> [times = List.DateTimes(#"Removed Columns1"[#"Date/Time"]{0}, 
                                                        Duration.TotalSeconds(#"Removed Columns1"[#"Date/Time"]{1}-#"Removed Columns1"[#"Date/Time"]{0})+1,
                                                        #duration(0,0,0,1)), IDX = 0],
                            each [IDX] < Table.RowCount(#"Removed Columns1"),
                            each [times = List.DateTimes(#"Removed Columns1"[#"Date/Time"]{[IDX]+2}, 
                                                        Duration.TotalSeconds(#"Removed Columns1"[#"Date/Time"]{[IDX]+3}-#"Removed Columns1"[#"Date/Time"]{[IDX]+2})+1,
                                                        #duration(0,0,0,1)), IDX = [IDX]+2],
                            each [times]
                                    )
                            ),

//filter the table using the list
filterTimesCol = Table.FromList(filterTimes,Splitter.SplitByNothing()),
filteredTable = Table.Join(#"Changed Type","Date/Time",filterTimesCol,"Column1",JoinKind.Inner),
    #"Removed Columns" = Table.RemoveColumns(filteredTable,{"Column1"}),
    #"Added Custom1" = Table.AddColumn(#"Removed Columns", "Custom", each DateTime.ToText([#"Date/Time"],"dd-MMM-yy")),
    #"Filtered Rows2" = Table.SelectRows(#"Added Custom1", each [#"Date/Time"] > #datetime(2019, 01, 01, 0, 0, 0)),
    #"Sorted Rows" = Table.Sort(#"Filtered Rows2",{{"Date/Time", Order.Ascending}})
in
    #"Sorted Rows"

Answer 1

I set up the below to return a sorted table with all results between the start and ending date/times. You can then select the first or middle or bottom row of each table if you want from this point. Its hard to tell from your question if you are looking for the value closest to the start value, closest to the end value or something inbetween. You can wrap my Table.Sort with a Table.FirstN or Table.LastN to pick up the first or last row.

I left most of your starting code alone

let Source = Table.Buffer(T1),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Date/Time", type datetime}, {"P7 [mbar]", Int64.Type}}),
//get start/stop times table
Source2 = T2,
typeIt = Table.TransformColumnTypes(Source2, {"Date/Time", type datetime}),
#"Filtered Rows" = Table.SelectRows(typeIt, each ([#"Date/Time"] <> null)),
#"Added Index" = Table.AddIndexColumn(#"Filtered Rows", "Index", 0, 1),
// shift Info up one row for comparison
    shiftedList = List.RemoveFirstN(  #"Added Index"[Info],1),
    custom1 = Table.ToColumns(  #"Added Index") & {shiftedList},
    custom2 = Table.FromColumns(custom1,Table.ColumnNames(  #"Added Index") & {"NextInfo"}),
#"Filtered Rows2" = Table.SelectRows(custom2, each not (Text.Contains([Info],"start", Comparer.OrdinalIgnoreCase) and Text.Contains([NextInfo],"start", Comparer.OrdinalIgnoreCase))),
#"Added Custom3" = Table.AddColumn(#"Filtered Rows2", "Type", each if Text.Contains(Text.Lower([Info]),"start") then "start" else if Text.Contains(Text.Lower([Info]),"finished") then "finished" else null),
 #"Removed Columns2" = Table.RemoveColumns(#"Added Custom3",{"Info", "NextInfo"}),
#"Added Custom1" = Table.AddColumn(#"Removed Columns2", "Custom", each if [Type]="start" then [Index] else null),
#"Filled Down" = Table.FillDown(#"Added Custom1",{"Custom"}),
#"Removed Columns" = Table.RemoveColumns(#"Filled Down",{"Index"}),
#"Pivoted Column" = Table.Pivot(#"Removed Columns", List.Distinct(#"Removed Columns"[Type]), "Type", "Date/Time"),
#"Added Custom2" = Table.AddColumn(#"Pivoted Column","Table",(i)=>Table.Sort(Table.SelectRows(T1, each [#"Date/Time"]>=i[start] and [#"Date/Time"]<=i[finished]),{{"Date/Time", Order.Ascending}}) , type table )
in #"Added Custom2"