I am willing to run a clustering algorithm on data records consisting in sets each one representing the features enabled at a certain time.

Is there any clustering algorithm you would recommend me to try out? In my first tests I'm experimenting with K-means, but maybe there is something more suitable.

Is there any distance function that works well with sets? I guess that there is something better than the Euclidean distance but I don't have may clue on how the better metric could look like.


Question: Without using dowels, how do I join 2x4s edge to edge to be 1.5" x 7"?
Answer: Strapping

You could use some form of strapping on the back side.



With this option, you can extend the strapping and use it to attach the whole bit to the workbench.



Bored Holes

You could bore holes on the edge of the top or bottom piece to about half the width of the board, then use screws to fasten the two boards together.



You'll likely want to use a drill press to bore the holes.

Glue

Since it's not going to be structural, you could simply glue the two boards together using wood glue.



Sliding Dovetail

If you want to get real fancy, a sliding dovetail would work.



Though with this joint, you'll loose a bit of overall height.