Filter a specific data structure

anupambit1797 

Do you wish to extract rows that contain "MAC Flow Control" and the 16 rows beneath it?

If so, below works.

Though it is very slow, not sure is it because my poor coding or just because the file is too large....

let
  Source = Table.FromColumns({Lines.FromBinary(File.Contents("OnePlus9Pro_SDX60_prachConfigurationIndex_40 successfull_RACH.txt"), null, null, 65001)}),
  AddFlag = Table.AddColumn(Source, "ContainsText", each Text.Contains([Column1], "MAC Flow Control")),
  GetRowIndices = List.Positions(AddFlag[ContainsText]),
  zipped = List.Zip({GetRowIndices, AddFlag[ContainsText]}),
  GetRelevantRowIndices = List.Transform(List.Select(zipped, each _{1} = true), each _{0}),
  ListGenerator = (x)=>List.Generate(() => x, each _ < x+16, each _ + 1),
  GetRelevantSlices = List.Transform(GetRelevantRowIndices, each ListGenerator(_)),
  IncludedRowIndices = List.Combine(GetRelevantSlices),
  RelevantRows = List.Transform(IncludedRowIndices, each AddFlag[Column1]{_}),
  #"Converted to table" = Table.FromList(RelevantRows, Splitter.SplitByNothing(), null, null, ExtraValues.Error)
in
  #"Converted to table"