ScatterElements#

  • Domain: ai.onnx

  • Since version: 18

ScatterElements takes three inputs data, updates, and indices of the same rank r >= 1 and an optional attribute axis that identifies an axis of data (by default, the outer-most axis, that is axis 0). The output of the operation is produced by creating a copy of the input data, and then updating its value to values specified by updates at specific index positions specified by indices. Its output shape is the same as the shape of data.

For each entry in updates, the target index in data is obtained by combining the corresponding entry in indices with the index of the entry itself: the index-value for dimension = axis is obtained from the value of the corresponding entry in indices and the index-value for dimension != axis is obtained from the index of the entry itself.

reduction allows specification of an optional reduction operation, which is applied to all values in updates tensor into output at the specified indices. In cases where reduction is set to “none”, indices should not have duplicate entries: that is, if idx1 != idx2, then indices[idx1] != indices[idx2]. For instance, in a 2-D tensor case, the update corresponding to the [i][j] entry is performed as below:

output[indices[i][j]][j] = updates[i][j] if axis = 0,
output[i][indices[i][j]] = updates[i][j] if axis = 1,

When reduction is set to some reduction function f, the update corresponding to the [i][j] entry is performed as below:

output[indices[i][j]][j] = f(output[indices[i][j]][j], updates[i][j]) if axis = 0,
output[i][indices[i][j]] = f(output[i][indices[i][j]], updates[i][j]) if axis = 1,

where the f is +, *, max or min as specified.

This operator is the inverse of GatherElements. It is similar to Torch’s Scatter operation.

(Opset 18 change): Adds max/min to the set of allowed reduction ops.

Example 1:

data = [
    [0.0, 0.0, 0.0],
    [0.0, 0.0, 0.0],
    [0.0, 0.0, 0.0],
]
indices = [
    [1, 0, 2],
    [0, 2, 1],
]
updates = [
    [1.0, 1.1, 1.2],
    [2.0, 2.1, 2.2],
]
output = [
    [2.0, 1.1, 0.0]
    [1.0, 0.0, 2.2]
    [0.0, 2.1, 1.2]
]

Example 2:

data = [[1.0, 2.0, 3.0, 4.0, 5.0]]
indices = [[1, 3]]
updates = [[1.1, 2.1]]
axis = 1
output = [[1.0, 1.1, 3.0, 2.1, 5.0]]

Inputs

  • data (T): Tensor of rank r >= 1.

  • indices (Tind): Tensor of int32/int64 indices, of r >= 1 (same rank as input). All index values are expected to be within bounds [-s, s-1] along axis of size s. It is an error if any of the index values are out of bounds.

  • updates (T): Tensor of rank r >=1 (same rank and shape as indices)

Outputs

  • output (T): Tensor of rank r >= 1 (same rank as input).

Attributes

  • axis (int): Which axis to scatter on. Negative value means counting dimensions from the back. Accepted range is [-r, r-1] where r = rank(data).

  • reduction (string): Type of reduction to apply: none (default), add, mul, max, min. ‘none’: no reduction applied. ‘add’: reduction using the addition operation. ‘mul’: reduction using the multiplication operation.’max’: reduction using the maximum operation.’min’: reduction using the minimum operation.

Type Constraints

  • T: Input and output types can be of any tensor type. Allowed types: tensor(bfloat16), tensor(bool), tensor(complex128), tensor(complex64), tensor(double), tensor(float), tensor(float16), tensor(int16), tensor(int32), tensor(int64), tensor(int8), tensor(string), tensor(uint16), tensor(uint32), tensor(uint64), tensor(uint8).

  • Tind: Constrain indices to integer types Allowed types: tensor(int32), tensor(int64).

Examples#

test_cc_scatter_elements_with_axis

Node:
  ScatterElements(data, indices, updates) -> (y)
  Attributes:
    axis = 1

Inputs:
  data: shape=(1, 5), dtype=float32
    [[1., 2., 3., 4., 5.]]
  indices: shape=(1, 2), dtype=int64
    [[1, 3]]
  updates: shape=(1, 2), dtype=float32
    [[1.1, 2.1]]

Outputs:
  y: shape=(1, 5), dtype=float32
    [[1. , 1.1, 3. , 2.1, 5. ]]

test_cc_scatter_elements_with_duplicate_indices

Node:
  ScatterElements(data, indices, updates) -> (y)
  Attributes:
    axis = 1
    reduction = "add"

Inputs:
  data: shape=(1, 5), dtype=float32
    [[1., 2., 3., 4., 5.]]
  indices: shape=(1, 2), dtype=int64
    [[1, 1]]
  updates: shape=(1, 2), dtype=float32
    [[1.1, 2.1]]

Outputs:
  y: shape=(1, 5), dtype=float32
    [[1. , 5.2, 3. , 4. , 5. ]]

test_cc_scatter_elements_with_negative_indices

Node:
  ScatterElements(data, indices, updates) -> (y)
  Attributes:
    axis = 1

Inputs:
  data: shape=(1, 5), dtype=float32
    [[1., 2., 3., 4., 5.]]
  indices: shape=(1, 2), dtype=int64
    [[ 1, -3]]
  updates: shape=(1, 2), dtype=float32
    [[1.1, 2.1]]

Outputs:
  y: shape=(1, 5), dtype=float32
    [[1. , 1.1, 2.1, 4. , 5. ]]

test_cc_scatter_elements_with_reduction_max

Node:
  ScatterElements(data, indices, updates) -> (y)
  Attributes:
    axis = 1
    reduction = "max"

Inputs:
  data: shape=(1, 5), dtype=float32
    [[1., 2., 3., 4., 5.]]
  indices: shape=(1, 2), dtype=int64
    [[1, 1]]
  updates: shape=(1, 2), dtype=float32
    [[1.1, 2.1]]

Outputs:
  y: shape=(1, 5), dtype=float32
    [[1. , 2.1, 3. , 4. , 5. ]]

test_cc_scatter_elements_with_reduction_min

Node:
  ScatterElements(data, indices, updates) -> (y)
  Attributes:
    axis = 1
    reduction = "min"

Inputs:
  data: shape=(1, 5), dtype=float32
    [[1., 2., 3., 4., 5.]]
  indices: shape=(1, 2), dtype=int64
    [[1, 1]]
  updates: shape=(1, 2), dtype=float32
    [[1.1, 2.1]]

Outputs:
  y: shape=(1, 5), dtype=float32
    [[1. , 1.1, 3. , 4. , 5. ]]

test_cc_scatter_elements_with_reduction_mul

Node:
  ScatterElements(data, indices, updates) -> (y)
  Attributes:
    axis = 1
    reduction = "mul"

Inputs:
  data: shape=(1, 5), dtype=float32
    [[1., 2., 3., 4., 5.]]
  indices: shape=(1, 2), dtype=int64
    [[1, 1]]
  updates: shape=(1, 2), dtype=float32
    [[1.1, 2.1]]

Outputs:
  y: shape=(1, 5), dtype=float32
    [[1.  , 4.62, 3.  , 4.  , 5.  ]]

test_cc_scatter_elements_without_axis

Node:
  ScatterElements(data, indices, updates) -> (y)

Inputs:
  data: shape=(3, 3), dtype=float32
    [[0., 0., 0.],
     [0., 0., 0.],
     [0., 0., 0.]]
  indices: shape=(2, 3), dtype=int64
    [[1, 0, 2],
     [0, 2, 1]]
  updates: shape=(2, 3), dtype=float32
    [[1. , 1.1, 1.2],
     [2. , 2.1, 2.2]]

Outputs:
  y: shape=(3, 3), dtype=float32
    [[2. , 1.1, 0. ],
     [1. , 0. , 2.2],
     [0. , 2.1, 1.2]]

Differences with previous version (16)#

SchemaDiff: ScatterElements (domain 'ai.onnx')

  • old version: 16

  • new version: 18

  • breaking: no

Documentation:

  • line similarity: 0.89 (+6/-8 lines)

--- ScatterElements v16
+++ ScatterElements v18
@@ -21,18 +21,16 @@
 output[indices[i][j]][j] = updates[i][j] if axis = 0,
 output[i][indices[i][j]] = updates[i][j] if axis = 1,
 ```
-When `reduction` is set to "add", the update corresponding to the [i][j] entry is performed as below:
+When `reduction` is set to some reduction function `f`, the update corresponding to the [i][j] entry is performed as below:
 ```
-output[indices[i][j]][j] += updates[i][j] if axis = 0,
-output[i][indices[i][j]] += updates[i][j] if axis = 1,
+output[indices[i][j]][j] = f(output[indices[i][j]][j], updates[i][j]) if axis = 0,
+output[i][indices[i][j]] = f(output[i][indices[i][j]], updates[i][j]) if axis = 1,
 ```
-When `reduction` is set to "mul", the update corresponding to the [i][j] entry is performed as below:
-```
-output[indices[i][j]][j] *= updates[i][j] if axis = 0,
-output[i][indices[i][j]] *= updates[i][j] if axis = 1,
-```
+where the `f` is `+`, `*`, `max` or `min` as specified.

 This operator is the inverse of GatherElements. It is similar to Torch's Scatter operation.
+
+(Opset 18 change): Adds max/min to the set of allowed reduction ops.

 Example 1:
 ```

Version History#