Pass Parameter as column name in custom column calculation

[Anonymous]

Example Table:

Origin	Destination	Scenario 1	Scenario 2	Scenario 3
A	B	10	11	12
B	C	6	3	2

Thank you in advance for helping me solve this problem! 

I have 2 parameters that define which 2 fields I want to use in a calculated new column. For example: A user selects Scenario 2 and Scenario 3 as Parameter 1 and Parameter 2, respectively. In a new calculated column I would see the results of Scenario 2 value - Scenario 3 value, as shown in the Calc Col below. What does the syntax look like to create this calculated column based on the user selected parameters?

Origin	Destination	Scenario 1	Scenario 2	Scenario 3	Calc Col
A	B	10	11	12	-1
B	C	6	3	2	1

[Anonymous · Accepted solution]

u could, peraphs use this sheme:

a function like this:

let
    newTab = (Col1,Col2)=>Table.AddColumn(Table, "newColumnName", each Record.Field(_, Col1)-Record.Field(_, Col2))

in
    newTab

which when invoked using the names of two columns of you table:

gives:

[Anonymous · Accepted solution]

u could, peraphs use this sheme:

a function like this:

let
    newTab = (Col1,Col2)=>Table.AddColumn(Table, "newColumnName", each Record.Field(_, Col1)-Record.Field(_, Col2))

in
    newTab

which when invoked using the names of two columns of you table:

gives:

[Anonymous · Accepted solution]

I think i figured it out. I modified your Function to be a simple addcolumn step:

Table.AddColumn(PreviousStep, "Delta", each Record.Field(_, #"Scenario 1")-Record.Field(_, #"Scenario 2"))

Where Scenario 1 and Scenario 2 are the query parameter names. Seems to work! 

[Anonymous]

Close! The only issue I am running into is the parameters are query parameters so I am not sure how to assign the query parameters to your function parameters? If that makes sense?