inverts selected keyframe values (* -1)
import maya.cmds as cmds
curves = cmds.keyframe(q=True, sl=True, n=True)
if curves:
for curve in curves:
key_times = cmds.keyframe(curve, q=True, sl=True, tc=True)
key_vals = cmds.keyframe(curve, q=True, sl=True, vc=True)
for i, frame in enumerate(key_times):
cmds.keyframe(curve, e=True, time=(frame,frame), absolute=True, vc=(key_vals[i]*-1))
else:
cmds.warning('No keys selected')