I might disagree with you on this. The people I would not keep as "friends" would be those who do not influence you to live a godly life, but lead you into sinning. The ones who do not hold your confidence in trust. The ones who are thoughtless with your feelings. The ones who selfishly use you.
Those I would not call "friends". They would be just people who are in my life that I would continue to pray for, forgive, and not spend too much time with.
You really want to surround yourself with people who bring out the best in you, and will not drain you continually. The ones who will laugh at life with you, the ones who will not make you feel you constantly have to walk on egg shells. That you can feel safe with. That embrace with love your weaknesses.