org.apache.mahout.vectorizer.encoders.Dictionary.java Source code

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Here is the source code for org.apache.mahout.vectorizer.encoders.Dictionary.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.mahout.vectorizer.encoders;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
* Assigns integer codes to strings as they appear.
*/
public class Dictionary {
    private final Map<String, Integer> dict = new LinkedHashMap<>();

    public int intern(String s) {
        if (!dict.containsKey(s)) {
            dict.put(s, dict.size());
        }
        return dict.get(s);
    }

    public List<String> values() {
        // order of keySet is guaranteed to be insertion order
        return new ArrayList<>(dict.keySet());
    }

    public int size() {
        return dict.size();
    }

    public static Dictionary fromList(Iterable<String> values) {
        Dictionary dict = new Dictionary();
        for (String value : values) {
            dict.intern(value);
        }
        return dict;
    }
}