Swapping top and bottom in Subtract


I need to compare two lists and report both list A - list b and list b - list A.

The only way I can see to do this is as follows:

Have I missed something?

If so would it be possible to add an option to Subtract to select between ‘Select Top from Bottom’ and 'Select Bottom from Top.

This may also apply to other similar transformations.


You have taken the correct approach. But I recommend Clone (which creates an exact copy) rather than Sample.

The advantage of using the Y position of the inputs is that you can see which is being subtracted from which at a glance.

I understand but my gut feeling is that there must be a more elegant way of doing this.

This approach is also potentially risky as the fix is broken if the the clone transform is accidentally moved below the Clipboard item in my example.

Great product by the way so please take my comments as an improvement opportunity rather than a criticism :slight_smile:

The alternative is to have an additional control in the Right pane to specify the order. But that also comes with its own issues. Especially for transforms like Join which can have any number of inputs.

Join only allows two inputs in my version (1.12.1):


Sorry, I meant Stack!

Shame, I got excited then as this would allow me to dispense with nested joins. :slight_smile:

I still think that my original suggestion works best:

This would only apply to Subtract and possibly any similar ‘non-symmetrical’ transforms.

This isn’t a major deal for me as I have a workaround and I’m not sure how many others would like/need this option so I imagine it wouldn’t be high priority for you.

I’ll bear it in mind. But it would be a big change for questionable gains. Especially for customers who have got use to the current approach.

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You can add a New Col to both lists. Name the col “List”.
For List A the new col can have the value A for list B the col value B.
Stack the Data
Use the unique transform to concat the list col.
The result will tell you which data rows are in list A only, list B, or in both.

Filter from there