gather

• namespace: Rindow\NeuralNetworks\Gradient\Func
• classname: Gather

Differentiable gather function.

Gathers slices from params according to indices. Gradients are propagated to params, but not to indices.

Methods

gather

$g->gather(
    Variable|NDArray $params,
    Variable|NDArray $indices,
    ?int $axis=null,
    ?int $batchDims=null,
    ?int $detailDepth=null,
    ?int $indexDepth=null,
) : Variable

Create and execute the function in the builder method

Arguments

• params: A Variable or NDArray to gather slices from. Implicitly create Variable for NDArray.
• indices: A Variable or NDArray of indices. Implicitly create Variable for NDArray. Gradients are not propagated to indices.

Options

• axis: Axis of params to gather.
• batchDims: Number of batch dimensions.
• detailDepth: Depth of the detail dimensions.
• indexDepth: Depth of the index dimensions.

use Rindow\Math\Matrix\MatrixOperator;
use Rindow\NeuralNetworks\Builder\NeuralNetworks;
$mo = new MatrixOperator();
$nn = new NeuralNetworks($mo);
$g = $nn->gradient();
$params = $g->Variable([[1,2],[3,4],[5,6]]);
$indices = $g->Variable([0,2]);
$c = $nn->with($tape=$g->GradientTape(),function() use ($g,$params,$indices) {
    return $g->gather($params,$indices,axis:0);
});
$dParams = $tape->gradient($c,$params);
echo $mo->toString($c)."\n";
echo $mo->toString($dParams)."\n";