Power Query next repeat cell value replace with null

[srehman]

Column A. Result Column PQ

3. 3
3. Null
1. 1
4. 4
7. 7
9. 9
9. Null
9. Null
9. Null
20. 20
20. Null
11. 11
8. 8
There is no dot sorry typing in mobile. Looking for simple solution in power query b.

 

[C Moore]

Add a faux rankif column using ideas here. Add a conditional column where rank 1 keeps its value and higher is null.

 

[JGordon11]

let
    Source = Excel.CurrentWorkbook(){[Name="Table8"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", Int64.Type}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
    #"Sorted Rows" = Table.Sort(#"Added Index",{{"Column1", Order.Ascending},"Index"}),
    #"Added Index1" = Table.AddIndexColumn(#"Sorted Rows", "Index.1", 0, 1, Int64.Type),
    #"Added Conditional Column" = Table.AddColumn(#"Added Index1", "Custom", each if [Column1] = #"Added Index1"[Column1]{[Index.1]-1} then null else [Column1]),
    #"Replaced Errors" = Table.ReplaceErrorValues(#"Added Conditional Column", {{"Custom", #"Added Index1"[Column1]{0}}}),
    #"Sorted Rows1" = Table.Sort(#"Replaced Errors",{{"Index", Order.Ascending}}),
    #"Removed Columns" = Table.RemoveColumns(#"Sorted Rows1",{"Column1", "Index", "Index.1"})
in
    #"Removed Columns"

 

[shaowu459]

= List.Accumulate(Source[Title],{},(x,y)=>x&(if List.Contains(x,y) then {null} else {y}))

Source table:

 

[shaowu459]

if there is duplicate value like below:

changed the code to :

= List.Accumulate(Source[Title],{},(x,y)=>x&(if y=List.Last(x) then {null} else {y}))

 

[shaowu459]

If the list contains lots of data, my solution in post #4 and #5 may show stack overflow error.