org.apache.lens.ml.AlgoArgParser.java Source code

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Here is the source code for org.apache.lens.ml.AlgoArgParser.java

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/**
 * 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.lens.ml;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * The Class AlgoArgParser.
 */
public final class AlgoArgParser {
    private AlgoArgParser() {
    }

    /**
     * The Class CustomArgParser.
     *
     * @param <E> the element type
     */
    public abstract static class CustomArgParser<E> {

        /**
         * Parses the.
         *
         * @param value the value
         * @return the e
         */
        public abstract E parse(String value);
    }

    /** The Constant LOG. */
    public static final Log LOG = LogFactory.getLog(AlgoArgParser.class);

    /**
     * Extracts feature names. If the algo has any parameters associated with @AlgoParam annotation, those are set
     * as well.
     *
     * @param algo the algo
     * @param args    the args
     * @return List of feature column names.
     */
    public static List<String> parseArgs(MLAlgo algo, String[] args) {
        List<String> featureColumns = new ArrayList<String>();
        Class<? extends MLAlgo> algoClass = algo.getClass();
        // Get param fields
        Map<String, Field> fieldMap = new HashMap<String, Field>();

        for (Field fld : algoClass.getDeclaredFields()) {
            fld.setAccessible(true);
            AlgoParam paramAnnotation = fld.getAnnotation(AlgoParam.class);
            if (paramAnnotation != null) {
                fieldMap.put(paramAnnotation.name(), fld);
            }
        }

        for (int i = 0; i < args.length; i += 2) {
            String key = args[i].trim();
            String value = args[i + 1].trim();

            try {
                if ("feature".equalsIgnoreCase(key)) {
                    featureColumns.add(value);
                } else if (fieldMap.containsKey(key)) {
                    Field f = fieldMap.get(key);
                    if (String.class.equals(f.getType())) {
                        f.set(algo, value);
                    } else if (Integer.TYPE.equals(f.getType())) {
                        f.setInt(algo, Integer.parseInt(value));
                    } else if (Double.TYPE.equals(f.getType())) {
                        f.setDouble(algo, Double.parseDouble(value));
                    } else if (Long.TYPE.equals(f.getType())) {
                        f.setLong(algo, Long.parseLong(value));
                    } else {
                        // check if the algo provides a deserializer for this param
                        String customParserClass = algo.getConf().getProperties().get("lens.ml.args." + key);
                        if (customParserClass != null) {
                            Class<? extends CustomArgParser<?>> clz = (Class<? extends CustomArgParser<?>>) Class
                                    .forName(customParserClass);
                            CustomArgParser<?> parser = clz.newInstance();
                            f.set(algo, parser.parse(value));
                        } else {
                            LOG.warn("Ignored param " + key + "=" + value + " as no parser found");
                        }
                    }
                }
            } catch (Exception exc) {
                LOG.error("Error while setting param " + key + " to " + value + " for algo " + algo);
            }
        }
        return featureColumns;
    }
}