tf.unsorted_segment_sum(data, segment_ids, num_segments, name=None)

tf.unsorted_segment_sum(data, segment_ids, num_segments, name=None)

See the guide: Math > Segmentation

Computes the sum along segments of a tensor.

Read the section on Segmentation for an explanation of segments.

Computes a tensor such that (output[i] = sum_{j...} data[j...] where the sum is over tuples j... such that segment_ids[j...] == i. Unlike SegmentSum, segment_ids need not be sorted and need not cover all values in the full range of valid values.

If the sum is empty for a given segment ID i, output[i] = 0.

num_segments should equal the number of distinct segment IDs.


  • data: A Tensor. Must be one of the following types: float32, float64, int64, int32, uint8, uint16, int16, int8, complex64, complex128, qint8, quint8, qint32, half.
  • segment_ids: A Tensor. Must be one of the following types: int32, int64. A tensor whose shape is a prefix of data.shape.
  • num_segments: A Tensor of type int32.
  • name: A name for the operation (optional).


A Tensor. Has the same type as data. Has same shape as data, except for the first segment_ids.rank dimensions, which are replaced with a single dimension which has size num_segments.

Defined in tensorflow/python/ops/