opennlp.tools.doccat.BagOfWordsFeatureGenerator.java Source code

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Here is the source code for opennlp.tools.doccat.BagOfWordsFeatureGenerator.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 opennlp.tools.doccat;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;

import opennlp.tools.util.featuregen.StringPattern;

/**
 * Generates a feature for each word in a document.
 */
public class BagOfWordsFeatureGenerator implements FeatureGenerator {

    private final boolean useOnlyAllLetterTokens;

    public BagOfWordsFeatureGenerator() {
        this(false);
    }

    BagOfWordsFeatureGenerator(boolean useOnlyAllLetterTokens) {
        this.useOnlyAllLetterTokens = useOnlyAllLetterTokens;
    }

    @Override
    public Collection<String> extractFeatures(String[] text, Map<String, Object> extraInformation) {
        Objects.requireNonNull(text, "text must not be null");
        Collection<String> bagOfWords = new ArrayList<>(text.length);

        for (String word : text) {
            if (useOnlyAllLetterTokens) {
                StringPattern pattern = StringPattern.recognize(word);

                if (pattern.isAllLetter())
                    bagOfWords.add("bow=" + word);
            } else {
                bagOfWords.add("bow=" + word);
            }
        }

        return bagOfWords;
    }
}