def lsf_from_sequence(landmarks_urls):
""" computer the lsf feature from a expression sequence """
from file_op import FileOp
landmarks_sequence = FileOp.read_landmarks_sequence(landmarks_urls)
lsf_sequence = []
for i in xrange(0, len(landmarks_urls)):
landmarks = landmarks_sequence[i]
landmarks_neural = landmarks_sequence[0]
lsf_document = LSF.lsf(landmarks, landmarks_neural) #get the lsf word feature from one image (document)
lsf_sequence.append(lsf_document)
return LSFSequence(landmarks_urls, landmarks_sequence, lsf_sequence)
