Gather

Versioned name: Gather-1

Category: Data movement operations

Short description: Gather operation takes slices of data in the first input tensor according to the indices specified in the second input tensor and axis from the third input.

Detailed description

output[:, ... ,:, i, ... , j,:, ... ,:] = input1[:, ... ,:, input2[i, ... ,j],:, ... ,:]


Where i is the value from the third input.

Attributes: Gather has no attributes

Inputs

• 1: Tensor with arbitrary data. Required.
• 2: Tensor with indices to gather. The values for indices are in the range [0, input1[axis] - 1]. Required.
• 3: Scalar or 1D tensor axis is a dimension index to gather data from. For example, axis equal to 1 means that gathering is performed over the first dimension. Negative value means reverse indexing. Allowed values are from [-len(input1.shape), len(input1.shape) - 1]. Required.

Outputs

• 1: The resulting tensor that consists of elements from the first input tensor gathered by indices from the second input tensor. Shape of the tensor is [input1.shape[:axis], input2.shape, input1.shape[axis + 1:]]

Example

<layer id="1" type="Gather" ...>
<input>
<port id="0">
<dim>6</dim>
<dim>12</dim>
<dim>10</dim>
<dim>24</dim>
</port>
<port id="1">
<dim>15</dim>
<dim>4</dim>
<dim>20</dim>
<dim>28</dim>
</port>
<port id="2"/> <!-- axis = 1 -->
</input>
<output>
<port id="2">
<dim>6</dim> <!-- embedded dimension from the 1st input -->
<dim>15</dim> <!-- embedded dimension from the 2nd input -->
<dim>4</dim> <!-- embedded dimension from the 2nd input -->
<dim>20</dim> <!-- embedded dimension from the 2nd input -->
<dim>28</dim> <!-- embedded dimension from the 2nd input -->
<dim>10</dim> <!-- embedded dimension from the 1st input -->
<dim>24</dim> <!-- embedded dimension from the 1st input -->
</port>
</output>
</layer>