Iteratively reduce keyframes on linear segments in Nuke

reducer.py

import math
DELTA = 0.0001

def is_linear_segment(before, current, after, delta):
	dx = after.x - before.x
	dy = after.y - before.y
	t = (current.x - before.x) / dx
	linear_y = before.y + (dy * t)
	return math.fabs(linear_y - current.y) < delta

# Iteratively removes keyframes in the passed AnimationCurve which are on a linear segment between the neighbouring keyframes
# until there are no such keyframes left on the curve
def reduce_animation(animCurve):
	keyframesRemoved = reduction_pass(animCurve)
	while keyframesRemoved > 0:
		keyframesRemoved = reduction_pass(animCurve)

# Removes all keyframes in the passed AnimationCurve which are on a linear segment between the neighbouring keyframes		 
def reduction_pass(curve):
	to_remove_at = []
	keys = curve.keys()
	# Scan all the keys in blocks of three, and remove the ones where the differential is small
	for idx, current in enumerate(keys):
		if idx == 0 or (idx + 1 == len(keys)):
			pass
		else:
			before, after = keys[idx-1], keys[idx+1]
			if is_linear_segment(before, current, after, DELTA):
				# bake the tangents on the before and the after
				before.interpolation = nuke.LINEAR
				after.interpolation =  nuke.LINEAR
				after.lslope = 0
				to_remove_at.append(current)
	# Delete keys when we are not iterating over them. Prudent.
	curve.removeKey(to_remove_at)
	print "Killed " + str(len(to_remove_at)) + " keys"
	return len(to_remove_at)
		
# k = nuke.selectedNode()["size"]
# reduce_animation(k.animation(0))

def simplify(): 
	u = nuke.Undo()
	u.begin()
	
	knob_names = nuke.animations() # Returns the animations names under this knob
	for knob_name_with_suffix in knob_names:
		# Since the names are like "translate.x" what we gotta do is to chop off the suffix
		knob_name = knob_name_with_suffix.split(".")[0]
		# so that we can get at the knob object and do...
		k = nuke.thisNode()[knob_name]
		for curve in k.animations():
			reduce_animation(curve) # bam!
	u.end()

# Add the command to the knob menu in the node bin
m = nuke.menu("Animation"); 
m.addCommand("Simplify curve", "simplify()")