Fill missing dates with previous value

Hi ddijstelbloem ,

Try this:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("bc5BDsAgCATAv3CWBLZq7VuI//9GpXiqcNpksoAZAaxgKBXqAvFZsXaaxUhvVoYAP62hT6rYysgQH7YD/QEd0ZRc90/tuOrxisU6cl3d+QI=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [MutationDate = _t, Partcode = _t, CumInvQty = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"MutationDate", type text}, {"Partcode", Int64.Type}, {"CumInvQty", Int64.Type}}),
    #"Changed Type with Locale" = Table.TransformColumnTypes(#"Changed Type", {{"MutationDate", type date}}, "en-GB"),
    #"Sorted Rows" = Table.Sort(#"Changed Type with Locale",{{"Partcode", Order.Ascending}, {"MutationDate", Order.Ascending}}),
    #"Added Index" = Table.AddIndexColumn(#"Sorted Rows", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "FilledMutationDate", each let EndDate_ =
let NextPartcode_ = try #"Added Index"[Partcode]{ [Index]  + 1 } otherwise null, NextDate_= try #"Added Index" [MutationDate] { [Index]  + 1 } otherwise null
in if [Partcode]=NextPartcode_ then Number.From(NextDate_)-1 else Number.From([MutationDate])
in {Number.From([MutationDate])..EndDate_}),
    #"Expanded FilledMutationDate" = Table.ExpandListColumn(#"Added Custom", "FilledMutationDate"),
    #"Changed Type1" = Table.TransformColumnTypes(#"Expanded FilledMutationDate",{{"FilledMutationDate", type date}}),
    #"Removed Columns" = Table.RemoveColumns(#"Changed Type1",{"MutationDate", "Index"}),
    #"Reordered Columns" = Table.ReorderColumns(#"Removed Columns",{"FilledMutationDate", "Partcode", "CumInvQty"})
in
    #"Reordered Columns"

Source Table:

Result Table:

...

Best Regards,

Icey

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