Concatenate (union of columns) many files from a given folder

Hi all,

(beginner here). I am trying to concatenate a large (n > 30) and variable number of excel files that have some row headers in common but share no column headers. I am able to do do that for n=2 and up to n=5 using more input ports in a Concatenate port, but (1) n is not known in advance and (2) I need to work with any number of files.

I could see solutions where files share a common structure (same headers) but that does not work here.

Just for the example here is what works with n=2:


(the relevant writer node is on the right, the others are just for debugging). The regex column renamer makes sure that all column headers are different.

This is what is needed/done:

I guess the way to go would be to use a loop that reads the files one at a time and concatenates it with an initially empty table but I have no idea how to do that.

Any help is welcome !


Are all your Excel files in the same folder or folder tree? If so, the Excel Reader node can be set up to load and concatenate them automatically. You’ll have to tweak the node settings (on the Advanced Settings tab) so that it doesn’t fail if specs differ.

I’ve uploaded an example workflow here.


Works great, I had not noticed the fail if specs differ switch.

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