Facebook friends list sorting - what algorithm is it based on?

Question

Facebook

Hello. Today I asked myself a question - what algorithm underlies the sorting of the list of friends when viewing it? It's just that at the top of the list is a person who has not been active on my page for about a week (like and comment on my posts), but has done this before for about a month and a half, with interruptions. Everything would be fine, but the second line is occupied by a person who is not active on my page at all, and for a very, very long time, but I sometimes “be active” on his page, but also quite rarely. The third line is one of the top friends. I googled on this topic, it turned out that there is an opinion that the position of a person in the list depends on how much he was interested in me. I note that the first person on the list is the person with whom I have been looking through the correspondence for the last 3-4 days, although I do not write anything.
I wonder if anyone can at least roughly know how this algorithm can work? Who decides here - me or a friend? It is also interesting to read opinions. Thanks in advance for your replies :)

Answer 1

It's a function of several variables:
1. The person's activity, the number of posts that hit your feed
2. The time and number of views of that person's posts in your feed
3. The number of "likes" and "shares" associated with that person's posts
4. The number of your replies and comments related to this person
5. Number of mutual friends
6. Number of views of the person's profile page
7. Number and duration of internal chat conversations with this user
All aimed at quickly finding a person with whom you are actively interacting among the entire list friends. A similar algorithm and Vkontakte.