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.transform;
018
019/**
020 * An interface for the statistics that need to be
021 * collected for a specific {@link Transformation} on
022 * a single feature.
023 * <p>
024 * TransformStatistics are purely a runtime collection,
025 * they should not be persisted, nor can be directly
026 * constructed.
027 */
028public interface TransformStatistics {
029
030    /**
031     * Observes a value and updates the statistics.
032     * @param value The value to observe.
033     */
034    public void observeValue(double value);
035
036    /**
037     * Observes a sparse (i.e., zero) value.
038     */
039    public void observeSparse();
040
041    /**
042     * Observes {@code count} sparse values.
043     * @param count The number of sparse values.
044     */
045    public void observeSparse(int count);
046
047    /**
048     * Generates the appropriate {@link Transformer}
049     * from the collected statistics.
050     * @return The Transformer.
051     */
052    public Transformer generateTransformer();
053
054}