python - Translate integers in a numpy array to a contiguous range 0...n -

i translate arbitrary integers in numpy array contiguous range 0...n, this:

source: [2 3 4 5 4 3] translating [2 3 4 5] -> [0 1 2 3] target: [0 1 2 3 2 1] 

there must better way following:

import numpy np  "translate arbitrary integers in source array contiguous range 0...n"  def translate_ids(source, source_ids, target_ids):     target = source.copy()      in range(len(source_ids)):         x = source_ids[i]         x_i = source == x         target[x_i] = target_ids[i]      return target  #  source = np.array([ 2, 3, 4, 5, 4, 3 ]) source_ids = np.unique(source) target_ids = np.arange(len(source_ids))  target = translate_ids(source, source_ids, target_ids)  print "source:", source print "translating", source_ids, '->', target_ids print "target:", target 

what it?

iiuc can use np.unique's optional argument return_inverse, -

np.unique(source,return_inverse=true)[1] 

sample run -

in [44]: source out[44]: array([2, 3, 4, 5, 4, 3])  in [45]: np.unique(source,return_inverse=true)[1] out[45]: array([0, 1, 2, 3, 2, 1])