001/*
002 * Copyright (c) 2015-2020, Oracle and/or its affiliates. All rights reserved.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.tribuo.data.columnar;
018
019import com.oracle.labs.mlrg.olcut.config.Configurable;
020import com.oracle.labs.mlrg.olcut.provenance.ConfiguredObjectProvenance;
021import com.oracle.labs.mlrg.olcut.provenance.Provenancable;
022
023import java.util.List;
024
025/**
026 * Takes a list of columnar features and adds new features or removes existing features.
027 * <p>
028 * Any existing features have their names preserved if they are not removed.
029 * <p>
030 * New features that are created must use the {@link ColumnarFeature#CONJUNCTION} String
031 * as their field name, as enforced by the two field {@link ColumnarFeature} constructor.
032 */
033public interface FeatureProcessor extends Configurable, Provenancable<ConfiguredObjectProvenance> {
034
035    /**
036     * Processes a list of {@link ColumnarFeature}s, transforming it
037     * by adding conjunctions or removing unnecessary features.
038     * @param features The list of features to process.
039     * @return A (possibly empty) list of features.
040     */
041    public List<ColumnarFeature> process(List<ColumnarFeature> features);
042
043}