Excel Power Query. Different Formulas for Each Row of Values from Other Rows

问题

I have a table 1 of 500+ rows that are updated multiple times during a month by a request. And there is a updated table of different formulas (200+) that should be calculated using values from table 1.

Table 1

year	product	value
1993	Apple	98.45
1994	Mushrooms	67.54
1992	Apple	95.45
2021	Melon	112.0

Table 2

id	formula
1	1994/1993*100-100
2	1994-1993
3	2021/1992*100-100

etc...

My way:

1. in table_1 I have created a key column - year.
2. I have modified the formula (below - a pic):

Code for table_2:

   let
        src = Excel.CurrentWorkbook(){[Name="table_2"]}[Content],
        pq_auto1 = Table.PromoteHeaders(src, [PromoteAllScalars=true]),
        pq_auto2 = Table.TransformColumnTypes(pq_auto1,{{"Id", Int64.Type}, {"formula", type text}}),
        result = Table.AddColumn(pq_auto2,"value",each Expression.Evaluate([modified_formula],#shared))
   in
        result

Can you suggest me to find a better way to do this calculations by each row?

回答1:

It is not possible to do that just like with Excel formula however BI Accountant showed elegant solution by shifting column by one row:

let
     Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content]
    ,ShiftedList = {null} & List.RemoveLastN(Table.Column(Source, "ColumnToBeShifted"), 1)
    ,NewShiftedColumn = Table.FromColumns(Table.ToColumns(Source) & {ShiftedList}, Table.ColumnNames(Source) & {"NewColumnName"})
in
    NewShiftedColumn

With this your calculation should be very easy.

来源：https://stackoverflow.com/questions/66090912/excel-power-query-different-formulas-for-each-row-of-values-from-other-rows