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DML_GATHER_ELEMENTS_OPERATOR_DESC structure (directml.h)

  • Article

Gathers elements from the input tensor along the given axis using the indices tensor to remap into the input. This operator performs the following pseudocode, with the exact behavior dependent on the axis, input dimension count, and indices dimension count.

output[i, j, k, ...] = input[index[i, j, k, ...], j, k, ...] // if axis == 0
output[i, j, k, ...] = input[i, index[i, j, k, ...], k, ...] // if axis == 1
output[i, j, k, ...] = input[i, j, index[i, j, k, ...], ...] // if axis == 2
...

Syntax

struct DML_GATHER_ELEMENTS_OPERATOR_DESC {
  const DML_TENSOR_DESC *InputTensor;
  const DML_TENSOR_DESC *IndicesTensor;
  const DML_TENSOR_DESC *OutputTensor;
  UINT                  Axis;
};

Members

InputTensor

Type: const DML_TENSOR_DESC*

The tensor to read from.

IndicesTensor

Type: const DML_TENSOR_DESC*

The indices into the input tensor along the active axis. The Sizes must match InputTensor.Sizes for every dimension except Axis.

Starting with DML_FEATURE_LEVEL_3_0, this operator supports negative index values when using a signed integral type with this tensor. Negative indices are interpreted as being relative to the end of the axis dimension. For example, an index of -1 refers to the last element along that dimension.

OutputTensor

Type: const DML_TENSOR_DESC*

The tensor to write the results to. The Sizes must match IndicesTensor.Sizes, and DataType must match InputTensor.DataType.

Axis

Type: UINT

The axis dimension of InputTensor to gather along, ranging [0, *InputTensor.DimensionCount*).

Examples

Axis = 0

InputTensor: (Sizes:{3,3}, DataType:FLOAT32)
    [[1, 2, 3],
     [4, 5, 6],
     [7, 8, 9]]

IndicesTensor: (Sizes:{2,3}, DataType:UINT32)
    [[1, 2, 0],
     [2, 0, 0]]

// output[y, x] = input[indices[y, x], x]
OutputTensor: (Sizes:{2,3}, DataType:UINT32)
    [[4, 8, 3], // select elements vertically from data
     [7, 2, 3]]

Availability

This operator was introduced in DML_FEATURE_LEVEL_2_1.

Tensor constraints

  • IndicesTensor, InputTensor, and OutputTensor must have the same DimensionCount.
  • InputTensor and OutputTensor must have the same DataType.

Tensor support

DML_FEATURE_LEVEL_4_1 and above

Tensor Kind Supported dimension counts Supported data types
InputTensor Input 1 to 8 FLOAT64, FLOAT32, FLOAT16, INT64, INT32, INT16, INT8, UINT64, UINT32, UINT16, UINT8
IndicesTensor Input 1 to 8 INT64, INT32, UINT64, UINT32
OutputTensor Output 1 to 8 FLOAT64, FLOAT32, FLOAT16, INT64, INT32, INT16, INT8, UINT64, UINT32, UINT16, UINT8

DML_FEATURE_LEVEL_3_0 and above

Tensor Kind Supported dimension counts Supported data types
InputTensor Input 1 to 8 FLOAT32, FLOAT16, INT32, INT16, INT8, UINT32, UINT16, UINT8
IndicesTensor Input 1 to 8 INT64, INT32, UINT64, UINT32
OutputTensor Output 1 to 8 FLOAT32, FLOAT16, INT32, INT16, INT8, UINT32, UINT16, UINT8

DML_FEATURE_LEVEL_2_1 and above

Tensor Kind Supported dimension counts Supported data types
InputTensor Input 4 FLOAT32, FLOAT16, INT32, INT16, INT8, UINT32, UINT16, UINT8
IndicesTensor Input 4 UINT32
OutputTensor Output 4 FLOAT32, FLOAT16, INT32, INT16, INT8, UINT32, UINT16, UINT8

Requirements

Requirement Value
Minimum supported client Windows 10 Build 20348
Minimum supported server Windows 10 Build 20348
Header directml.h