TensorAddress combine(TensorAddress sparsePart, TensorAddress densePart) {
            var addrBuilder = new TensorAddress.Builder(fullType);
            var sparseDims = sparseType.dimensions();
            for (int i = 0; i < sparseDims.size(); i++) {
                var dim = sparseDims.get(i);
                addrBuilder.add(dim.name(), sparsePart.objectLabel(i));
            }
            var denseDims = denseType.dimensions();
            for (int i = 0; i < denseDims.size(); i++) {
                var dim = denseDims.get(i);
                addrBuilder.add(dim.name(), densePart.objectLabel(i));
            }
            return addrBuilder.build();
        }
The <i>filter_subspaces</i> tensor function selects some cells or subspaces in a mapped or mixed tensor

@author arnej
vespajlib/src/main/java/com/yahoo/tensor/functions/FilterSubspaces.java