Ha Rav, I had pants and two sweaters in a pile, I spread them out on the bed, took the sweater I wanted, did I do Borer and break Shabbos?
Thank you for the question.
It is not considered borer for two reasons. The first is that large items in a pile such as your pants and sweaters would not be considered a mixture, (it would have to be 4-5), therefore borer doesn’t apply to them. Secondly, if you scatter the items, and disintegrated the mixture, borer will no longer apply them.
Aruch Hashulchan O:CH 319-17, Shabbos 72a, Igros Moshe Y:D 4 74 Borer 11, Shmiras Shabbos Khilchoso 3 ftnt. 7.