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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package ai.vespa.embedding;
import com.yahoo.tensor.Tensor;
import com.yahoo.tensor.TensorAddress;
import com.yahoo.tensor.TensorType;
/**
* @author bjorncs
*/
public enum PoolingStrategy {
MEAN {
@Override
public Tensor toSentenceEmbedding(TensorType type, Tensor tokenEmbeddings, Tensor attentionMask) {
var builder = Tensor.Builder.of(type);
var summedEmbeddings = tokenEmbeddings.sum("d1");
var summedAttentionMask = attentionMask.expand("d0").sum("d1");
var averaged = summedEmbeddings.join(summedAttentionMask, (x, y) -> x / y);
for (int i = 0; i < type.dimensions().get(0).size().get(); i++) {
builder.cell(averaged.get(TensorAddress.of(0, i)), i);
}
return builder.build();
}
},
CLS {
@Override
public Tensor toSentenceEmbedding(TensorType type, Tensor tokenEmbeddings, Tensor ignored) {
var builder = Tensor.Builder.of(type);
for (int i = 0; i < type.dimensions().get(0).size().get(); i++) {
builder.cell(tokenEmbeddings.get(TensorAddress.of(0,0,i)), i);
}
return builder.build();
}
};
public abstract Tensor toSentenceEmbedding(TensorType type, Tensor tokenEmbeddings, Tensor attentionMask);
public static PoolingStrategy fromString(String strategy) {
return switch (strategy.toLowerCase()) {
case "mean" -> MEAN;
case "cls" -> CLS;
default -> throw new IllegalArgumentException("Unknown pooling strategy '%s'".formatted(strategy));
};
}
}
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