| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.solr.analytics.function.mapping; |
| |
| import org.apache.solr.analytics.ExpressionFactory.CreatorFunction; |
| import org.apache.solr.analytics.value.DoubleValue; |
| import org.apache.solr.analytics.value.DoubleValueStream; |
| import org.apache.solr.common.SolrException; |
| import org.apache.solr.common.SolrException.ErrorCode; |
| |
| /** |
| * A logarithm mapping function. |
| * <p> |
| * Uses: |
| * <ul> |
| * <li>If one numeric Value or ValueStream is passed in, a {@link DoubleValue} or {@link DoubleValueStream} |
| * representing the natural logarithm is returned. |
| * <li>If two numeric Values are passed in, a {@link DoubleValue} representing the logarithm of the first with the second as the base is returned. |
| * <li>If a numeric ValueStream and a numeric Value are passed in, a {@link DoubleValueStream} representing the logarithm of |
| * the Value with each of the values of the ValueStream for a document as the base is returned. |
| * (Or the other way, since the Value and ValueStream can be used in either order) |
| * </ul> |
| */ |
| public class LogFunction { |
| public static final String name = "log"; |
| public static final CreatorFunction creatorFunction = (params -> { |
| if (params.length == 0) { |
| throw new SolrException(ErrorCode.BAD_REQUEST,"The "+name+" function requires at least 1."); |
| } else if (params.length == 1) { |
| return LambdaFunction.createDoubleLambdaFunction(name, (a) -> Math.log(a), (DoubleValueStream)params[0]); |
| } else if (params.length == 2) { |
| return LambdaFunction.createDoubleLambdaFunction(name, (a,b) -> Math.log(a)/Math.log(b), (DoubleValueStream)params[0], (DoubleValueStream)params[1]); |
| } else { |
| throw new SolrException(ErrorCode.BAD_REQUEST,"The "+name+" function accepts at most 2 paramaters, " + params.length + " found."); |
| } |
| }); |
| } |