Custom column - "best of these choices"

[RMDNA]

Hi all,

I have a table (see below) with the Absolute Percent Error of three different models. I'd like to create a custom column with the "best" (lowest APE) of those three.

In Excel, I have =MIN(Table[@[Model 1 APE]:[Model 3 APE]])

What's the PQ equivalent? I'm unsure how to specify a range of columns.

As usual, thanks!

[SteveCampbell · Accepted solution]

So really, we should not use a calculated column in DAX. It will result in the column being recaulclated every time and slow performance.

You could write a measure, which would not store a value for every row. As you asked for a column, instead, we should do this in the query editor. This will mean it is only calculated on a data refresh, and stored in the model.

In the query editor, go to the query, and select "Add Custom Column".

The code you can use is:

each if [Model 1 APE] = [Model 2 APE]then "N/A"

else if [Model 1 APE]< [Model 2 APE] then "Model 1 APE"
else if [Model 2 APE]< [Model 1 APE] then "Model 2 APE"

else "N/A"

Here, the second else if statement is a bit redundant, but I left it in so that you can add more logic if you wanted, to compare more models. You can add as many "else if" statements to use any logic you wish.

[RMDNA]

Wow. Somehow, after almost three years of using Power BI, I entirely forgot about the Conditional Column button. Thanks for the support!

[SteveCampbell]

You can try:

New Column = 
_min_amnt = min([Model 1 APE],min([Model 2 APE],[Model 3 APE])

RETURN 

SWITCH( _min_amnt, 
  [Model 1 APE], "Model 1 APE",
  [Model 2 APE], "Model 2 APE",
  [Model 3 APE], "Model 3 APE",
  "None"
)

Although, this will not work in case of ties, and pick the first. What would be the desired solution if all 0, for example?

[RMDNA]

@SteveCampbell,

How about with two columns (Model 1 and 2)? In the case of a tie/all zero, display "N/A."