how to get the previous value taking into account other columns as a filter

[Anonymous]

Date	Value	Type	Category	Value Before
1/1/2020	10.1	1	A
1/15/2020	10.2	2	A
2/2/2020	10.3	2	B
2/17/2020	10.4	2	A	10.2
3/7/2020	10.5	2	A	10.4
3/20/2020	10.6	1	A	10.1

I have an table like that and I need to get the value before taking into account the columns Type and Category. Realize that I don't have values for every day.

For example, if I'm analyzing the day 2/17/2020, the value is 10.4, type 2 and Category A. The Value Before this one has to be of the same type and category, so we need to take the 10.2 of the day 1/15/2020.

[CNENFRNL · Accepted solution]

Value Before = 
VAR __d = MAX( INFO[Date] )
VAR __t =
    CALCULATETABLE(
        INFO,
        ALLEXCEPT( INFO, INFO[Category], INFO[Type] ),
        INFO[Date] < __d
    )
RETURN
    MAXX( TOPN( 1, __t, INFO[Date] ), INFO[Value] )

[v-yingjl · Accepted solution]

Hi @Anonymous ,

You can try this query:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMtQ31DcyMDJQ0lFSMDTQMwTSIOyoFKsDljRFljUC0kZwWSN9I2RJY6ikE1TS0BxZ1gRFq7E+iqQpmqSRAbKsGcJNsQA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Date = _t, Value = _t, Type = _t, Category = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Value", type number}, {"Type", Int64.Type}, {"Category", type text}}),
    #"Grouped Rows" = 
        Table.Group(
            #"Changed Type", {"Type", "Category"}, 
            {
                {"Data", 
                    each 
                    let tab = Table.AddIndexColumn(Table.Sort(_,{"Date",Order.Ascending}),"Index",1,1) in 
                    Table.AddColumn(
                        tab,"New",
                        (x) => try Table.Max(Table.SelectRows(tab,(y) => y[Index] = x[Index] - 1),"Index")[Value] otherwise null
                    ), 
                    type table [Date=nullable date, Value=nullable number, Type=nullable number, Category=nullable text]
                }
            }
        ),
    #"Removed Columns" = Table.RemoveColumns(#"Grouped Rows",{"Type", "Category"}),
    #"Expanded Data" = Table.ExpandTableColumn(#"Removed Columns", "Data", {"Date", "Value", "Type", "Category","New"}, {"Date", "Value", "Type", "Category","Value Before"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Expanded Data",{{"Date", type date}, {"Value", type number}, {"Type", Int64.Type}, {"Category", type text}, {"Value Before", type number}}),
    #"Sorted Rows" = Table.Sort(#"Changed Type1",{{"Date", Order.Ascending}})
in
    #"Sorted Rows"

Best Regards,
Community Support Team _ Yingjie Li
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[CNENFRNL · Accepted solution]

Value Before = 
VAR __d = MAX( INFO[Date] )
VAR __t =
    CALCULATETABLE(
        INFO,
        ALLEXCEPT( INFO, INFO[Category], INFO[Type] ),
        INFO[Date] < __d
    )
RETURN
    MAXX( TOPN( 1, __t, INFO[Date] ), INFO[Value] )