Date since last added in Power Query or DAX

[mshilendhari]

Hi all,

I have a scenario where I need to show the date when a part became watchlist. Data is in the format shown below and this is filtered for one part. In this example, this part was initially on watchlist from 6/25 to 6/29 and then again it became watchlist from 8/9 till today. What I am looking for as date when last added is 8/9. However, since there is no other differentiating category, its always giving me 6/25 as the date when it was last added. Please help on how to achieve this use case. It would be great if you can help me with a solution using Power Query as I am showing a lot of columns in the dashboard in tabular format. So anything on DAX might end up using a lot of CPU/memory. Thanks much in advance!

[edhans]

@mshilendhari - see if this is what you want. If not, please provide data per links below and how the calculation should be arrived at. The below M code turns this:

into this. You can see the items in red retain the latest Watchlist date for the same item.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUbLUN9Q3MjAyADLDE0uSM3Iyi0uUYnVgkkb4JI1hkp55xQWpySWZ+XlIsibYtToBRSxwWQqRxGEpRNIYn6QJDhdBZE2xycYCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Item = _t, Date = _t, Status = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}}),
    #"Grouped Rows" = 
        Table.Group(
            #"Changed Type", 
            {"Item"}, 
            {
                {
                    "WatchListDate",
                    each
                        let
                            varStatus = "Watchlist",
                            varGroupTable = _
                        in
                    
                    Table.AddColumn(
                        _,
                        "Test",
                        each
                            let
                                varCurrentDate = [Date]
                            in
                            List.Max(
                                Table.SelectRows(
                                    varGroupTable,
                                    each [Status] = varStatus and [Date] <= varCurrentDate
                                )[Date]
                            )
                    )
                    
                }
            }
        ),
    #"Expanded WatchListDate" = Table.ExpandTableColumn(#"Grouped Rows", "WatchListDate", {"Date", "Status", "Test"}, {"Date", "Status", "Test"})
in
    #"Expanded WatchListDate"

How to get good help fast. Help us help you.
How to Get Your Question Answered Quickly
How to provide sample data in the Power BI Forum

How to use M code provided in a blank query:
1) In Power Query, select New Source, then Blank Query
2) On the Home ribbon, select "Advanced Editor" button
3) Remove everything you see, then paste the M code I've given you in that box.
4) Press Done
5) See this article if you need help using this M code in your model.

[Greg_Deckler]

@mshilendhari - What is the logic to arrive at that date? The minimum date after the last >1 day gap? @ImkeF and @edhans might have a Power Query solution. Otherwise, would need to use something like MTBF to calculate a column with difference in day from previous and then another calculated column to flag the date. Calculated columns might not be so bad as this would be part of refresh.

See my article on Mean Time Between Failure (MTBF) which uses EARLIER: http://community.powerbi.com/t5/Community-Blog/Mean-Time-Between-Failure-MTBF-and-Power-BI/ba-p/3395....
The basic pattern is:
Column = 
  VAR __Current = [Value]
  VAR __Previous = MAXX(FILTER('Table','Table'[Date] < EARLIER('Table'[Date])),[Value])
RETURN
  __Current - __Previous

[amitchandak]

@mshilendhari , continuous Streak problem.

I think is memory consuming. I have a blog that deals with different use case

https://community.powerbi.com/t5/Community-Blog/Power-BI-Continuous-Streak-With-One-Day-Break/ba-p/1...

see if this can help