Anger in a dream commonly surfaces when a boundary has been crossed and the frustration around it hasn't had anywhere to go in waking life. Lashing out at someone in the dream can point to injustice you've been absorbing quietly, a reaction you've suppressed that's finally demanding to be felt, if not yet spoken.
It behooves the astrologer to consider the time in directions of the planets; but in the fixed stars it is not so needful. - William Lilly (1602.-1681.)