def makeClassAverages(lst, outputstack, classdata, params):
#align images in class
images = EMAN.readImages(lst, -1, -1, 0)
for image in images:
image.rotateAndTranslate()
if image.isFlipped():
image.hFlip()
#make class average
avg = EMAN.EMData()
avg.makeMedian(images)
#write class average
e = EMAN.Euler()
alt = classdata['euler1'] * math.pi / 180
az = classdata['euler2'] * math.pi / 180
phi = 0.0
e.setAngle(alt, az, phi)
avg.setRAlign(e)
avg.setNImg(len(images))
avg.applyMask(params['mask'], 0)
avg.writeImage(outputstack, -1)
