# tf.raw_ops.UnsortedSegmentSum

Computes the sum along segments of a tensor.

#### View aliases


**Compat aliases for migration**

See
[Migration guide](https://www.tensorflow.org/guide/migrate) for
more details.

[`tf.compat.v1.raw_ops.UnsortedSegmentSum`](https://www.tensorflow.org/api_docs/python/tf/raw_ops/UnsortedSegmentSum)

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    tf.raw_ops.UnsortedSegmentSum(
        data, segment_ids, num_segments, name=None
    )

Read
[the section on segmentation](https://tensorflow.org/api_docs/python/tf/math#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`.
If the given segment ID `i` is negative, the value is dropped and will not be
added to the sum of the segment.

`num_segments` should equal the number of distinct segment IDs.

> [!CAUTION]
> **Caution:** On CPU, values in `segment_ids` are always validated to be less than `num_segments`, and an error is thrown for out-of-bound indices. On GPU, this does not throw an error for out-of-bound indices. On Gpu, out-of-bound indices result in safe but unspecified behavior, which may include ignoring out-of-bound indices or outputting a tensor with a 0 stored in the first dimension of its shape if `num_segments` is 0.

![](https://www.tensorflow.org/images/UnsortedSegmentSum.png)

    c = [[1,2,3,4], [5,6,7,8], [4,3,2,1]]
    tf.math.unsorted_segment_sum(c, [0, 1, 0], num_segments=2).numpy()
    array([[5, 5, 5, 5],
           [5, 6, 7, 8]], dtype=int32)

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| ## Args ||
|---|---|
| `data` | A `Tensor`. Must be one of the following types: `float32`, `float64`, `int32`, `uint8`, `int16`, `int8`, `complex64`, `int64`, `qint8`, `quint8`, `qint32`, `bfloat16`, `qint16`, `quint16`, `uint16`, `complex128`, `half`, `uint32`, `uint64`. |
| `segment_ids` | A `Tensor`. Must be one of the following types: `int16`, `int32`, `int64`. A tensor whose shape is a prefix of `data.shape`. The values must be less than `num_segments`. <br /> > [!CAUTION] > **Caution:** The values are always validated to be in range on CPU, never validated on GPU. |
| `num_segments` | A `Tensor`. Must be one of the following types: `int32`, `int64`. |
| `name` | A name for the operation (optional). |

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| ## Returns ||
|---|---|
| A `Tensor`. Has the same type as `data`. ||

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