code: def encodeIntoArray(self, value, output):
      
      denseInput = numpy.zeros(output.shape)
      try:
        denseInput[value] = 1
      except IndexError:
        if isinstance(value, numpy.ndarray):
          raise ValueError(
              "Numpy array must have integer dtype but got {}".format(
                  value.dtype))
        raise
      super(SparsePassThroughEncoder, self).encodeIntoArray(denseInput, output)
docs: See method description in base.py