Replace null with median

[neonguyen1803]

Dear all,

I have the data below: 

I want to replace the value null in column Week 1-2-3-4 with Median Column for each row --> it's mean for row 5, null value in Week 2 will be replaced to 8 (based on Median Column value in row 5 is 8 )

Thanks

[AlienSx · Accepted solution]

Hello, @neonguyen1803 if your table has nulls only in columns Week 1..4 then 

let
    Source = your_table,
    lst = Table.FromList(
            Table.ToList(
                Source, (x) => List.ReplaceValue(x, null, List.Last(x), Replacer.ReplaceValue)
            ), (x) => x, Table.ColumnNames(Source)
    )
in
    lst

[ronrsnfld · Accepted solution]

You can do this using the Table.ReplaceValue function with appropriate arguments to look at the Median column for the replacement value.

If your values might include decimals, be sure to set the data types to number rather than Int64.Type.

#"Replace Columns" = List.Select(Table.ColumnNames(#"Previous Step"), each Text.StartsWith(_,"Week")),
    #"Replace Nulls with Median" = Table.ReplaceValue(#"Previous Step",
        null,
        each [Median],
        Replacer.ReplaceValue,
        #"Replace Columns"),
    #"Reset Data Types" = Table.TransformColumnTypes(#"Replace Nulls with Median", List.Transform(#"Replace Columns", each {_, type number}))
in
    #"Reset Data Types"

[AlienSx · Accepted solution]

Hello, @neonguyen1803 if your table has nulls only in columns Week 1..4 then 

let
    Source = your_table,
    lst = Table.FromList(
            Table.ToList(
                Source, (x) => List.ReplaceValue(x, null, List.Last(x), Replacer.ReplaceValue)
            ), (x) => x, Table.ColumnNames(Source)
    )
in
    lst