Java Array Flatten flattenNTriples(final String[] values)

Description

Flatten a list of triples to n-tuples containing many objects for the same subject/predicate pair.

License

Open Source License

Parameter

Parameter	Description
values	The list of n-triples.

Return

The n-tuples concatenated.

Declaration

public static String flattenNTriples(final String[] values) 

Method Source Code

//package com.java2s;
/**/*from   ww  w.j a  v  a2  s .c  o m*/
 * Copyright (c) 2014, Sindice Limited. All Rights Reserved.
 *
 * This file is part of the SIREn project.
 *
 * SIREn is a free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * SIREn is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.HashMap;
import java.util.Map;

public class Main {
    /**
     * Flatten a list of triples to n-tuples containing many objects for the same
     * subject/predicate pair. Generate one n-tuple per subject/predicate pair.
     * <br>
     * This is useful for the document-centric indexing approach. The flatten
     * representation is more efficient in term of index size than the plain
     * n-triples approach.
     *
     * @param values The list of n-triples.
     * @return The n-tuples concatenated.
     */
    public static String flattenNTriples(final String[] values) {
        final Map<String, StringBuilder> map = new HashMap<String, StringBuilder>();
        return flattenNTriples(values, map);
    }

    /**
     * Flatten a list of triples to n-tuples containing many objects for the same
     * subject/predicate pair. Generate one n-tuple per subject/predicate pair.
     * <br>
     * This is useful for the document-centric indexing approach. The flatten
     * representation is more efficient in term of index size than the plain
     * n-triples approach.
     *
     * @param values The list of n-triples.
     * @return The n-tuples concatenated.
     */
    private static String flattenNTriples(final String[] values, final Map<String, StringBuilder> map) {
        for (final String value : values) {
            if (value != null) {
                final int firstWhitespace = value.indexOf(' ');
                final int secondWhitespace = value.indexOf(' ', firstWhitespace + 1);
                final int lastDot = value.lastIndexOf('.');
                if (firstWhitespace == -1 || secondWhitespace == -1 || lastDot == -1) {
                    continue; // probably invalid triple, just skip it
                }
                final String key = value.substring(0, secondWhitespace);
                final String object = value.substring(secondWhitespace, lastDot - 1);
                StringBuilder tb = map.get(key);
                if (tb == null) {
                    tb = new StringBuilder();
                    tb.append(key);
                    map.put(key, tb);
                }
                tb.append(object);
            }
        }
        final StringBuilder result = new StringBuilder();
        for (final StringBuilder tb : map.values()) {
            result.append(tb).append('.').append("\n");
        }
        return result.toString();
    }
}

Related

1. flattenArray(Object... objects)
2. flattenArray(Object[] words)
3. flattenArray(String[] aString)
4. flattenBytes(byte[] b)
5. flattenIndices(int[] indices, int[] extents)
6. flattenStringArray(String[] s_array, String delimiter)