001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.math.linear;
019    
020    import java.text.FieldPosition;
021    import java.text.NumberFormat;
022    import java.text.ParseException;
023    import java.text.ParsePosition;
024    import java.util.ArrayList;
025    import java.util.List;
026    import java.util.Locale;
027    
028    import org.apache.commons.math.MathRuntimeException;
029    import org.apache.commons.math.util.CompositeFormat;
030    
031    /**
032     * Formats a vector in components list format "{v0; v1; ...; vk-1}".
033     * <p>The prefix and suffix "{" and "}" and the separator "; " can be replaced by
034     * any user-defined strings. The number format for components can be configured.</p>
035     * <p>White space is ignored at parse time, even if it is in the prefix, suffix
036     * or separator specifications. So even if the default separator does include a space
037     * character that is used at format time, both input string "{1;1;1}" and
038     * " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
039     * returned. In the second case, however, the parse position after parsing will be
040     * just after the closing curly brace, i.e. just before the trailing space.</p>
041     *
042     * @version $Revision: 783702 $ $Date: 2009-06-11 04:54:02 -0400 (Thu, 11 Jun 2009) $
043     * @since 2.0
044     */
045    public class RealVectorFormat extends CompositeFormat {
046    
047        /** Serializable version identifier */
048        private static final long serialVersionUID = -708767813036157690L;
049    
050        /** The default prefix: "{". */
051        private static final String DEFAULT_PREFIX = "{";
052    
053        /** The default suffix: "}". */
054        private static final String DEFAULT_SUFFIX = "}";
055    
056        /** The default separator: ", ". */
057        private static final String DEFAULT_SEPARATOR = "; ";
058    
059        /** Prefix. */
060        private final String prefix;
061    
062        /** Suffix. */
063        private final String suffix;
064    
065        /** Separator. */
066        private final String separator;
067    
068        /** Trimmed prefix. */
069        private final String trimmedPrefix;
070    
071        /** Trimmed suffix. */
072        private final String trimmedSuffix;
073    
074        /** Trimmed separator. */
075        private final String trimmedSeparator;
076    
077        /** The format used for components. */
078        private NumberFormat format;
079    
080        /**
081         * Create an instance with default settings.
082         * <p>The instance uses the default prefix, suffix and separator:
083         * "{", "}", and "; " and the default number format for components.</p>
084         */
085        public RealVectorFormat() {
086            this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, getDefaultNumberFormat());
087        }
088    
089        /**
090         * Create an instance with a custom number format for components.
091         * @param format the custom format for components.
092         */
093        public RealVectorFormat(final NumberFormat format) {
094            this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
095        }
096    
097        /**
098         * Create an instance with custom prefix, suffix and separator.
099         * @param prefix prefix to use instead of the default "{"
100         * @param suffix suffix to use instead of the default "}"
101         * @param separator separator to use instead of the default "; "
102         */
103        public RealVectorFormat(final String prefix, final String suffix,
104                                final String separator) {
105            this(prefix, suffix, separator, getDefaultNumberFormat());
106        }
107    
108        /**
109         * Create an instance with custom prefix, suffix, separator and format
110         * for components.
111         * @param prefix prefix to use instead of the default "{"
112         * @param suffix suffix to use instead of the default "}"
113         * @param separator separator to use instead of the default "; "
114         * @param format the custom format for components.
115         */
116        public RealVectorFormat(final String prefix, final String suffix,
117                                final String separator, final NumberFormat format) {
118            this.prefix      = prefix;
119            this.suffix      = suffix;
120            this.separator   = separator;
121            trimmedPrefix    = prefix.trim();
122            trimmedSuffix    = suffix.trim();
123            trimmedSeparator = separator.trim();
124            this.format      = format;
125        }
126    
127        /**
128         * Get the set of locales for which real vectors formats are available.
129         * <p>This is the same set as the {@link NumberFormat} set.</p>
130         * @return available real vector format locales.
131         */
132        public static Locale[] getAvailableLocales() {
133            return NumberFormat.getAvailableLocales();
134        }
135    
136        /**
137         * Get the format prefix.
138         * @return format prefix.
139         */
140        public String getPrefix() {
141            return prefix;
142        }
143    
144        /**
145         * Get the format suffix.
146         * @return format suffix.
147         */
148        public String getSuffix() {
149            return suffix;
150        }
151    
152        /**
153         * Get the format separator between components.
154         * @return format separator.
155         */
156        public String getSeparator() {
157            return separator;
158        }
159    
160        /**
161         * Get the components format.
162         * @return components format.
163         */
164        public NumberFormat getFormat() {
165            return format;
166        }
167    
168        /**
169         * Returns the default real vector format for the current locale.
170         * @return the default real vector format.
171         */
172        public static RealVectorFormat getInstance() {
173            return getInstance(Locale.getDefault());
174        }
175    
176        /**
177         * Returns the default real vector format for the given locale.
178         * @param locale the specific locale used by the format.
179         * @return the real vector format specific to the given locale.
180         */
181        public static RealVectorFormat getInstance(final Locale locale) {
182            return new RealVectorFormat(getDefaultNumberFormat(locale));
183        }
184    
185        /**
186         * This static method calls {@link #format(Object)} on a default instance of
187         * RealVectorFormat.
188         *
189         * @param v RealVector object to format
190         * @return A formatted vector
191         */
192        public static String formatRealVector(RealVector v) {
193            return getInstance().format(v);
194        }
195    
196        /**
197         * Formats a {@link RealVector} object to produce a string.
198         * @param vector the object to format.
199         * @param toAppendTo where the text is to be appended
200         * @param pos On input: an alignment field, if desired. On output: the
201         *            offsets of the alignment field
202         * @return the value passed in as toAppendTo.
203         */
204        public StringBuffer format(RealVector vector, StringBuffer toAppendTo,
205                                   FieldPosition pos) {
206    
207            pos.setBeginIndex(0);
208            pos.setEndIndex(0);
209    
210            // format prefix
211            toAppendTo.append(prefix);
212    
213            // format components
214            for (int i = 0; i < vector.getDimension(); ++i) {
215                if (i > 0) {
216                    toAppendTo.append(separator);
217                }
218                formatDouble(vector.getEntry(i), format, toAppendTo, pos);
219            }
220    
221            // format suffix
222            toAppendTo.append(suffix);
223    
224            return toAppendTo;
225    
226        }
227    
228        /**
229         * Formats a object to produce a string.
230         * <p><code>obj</code> must be a  {@link RealVector} object. Any other type of
231         * object will result in an {@link IllegalArgumentException} being thrown.</p>
232         * @param obj the object to format.
233         * @param toAppendTo where the text is to be appended
234         * @param pos On input: an alignment field, if desired. On output: the
235         *            offsets of the alignment field
236         * @return the value passed in as toAppendTo.
237         * @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
238         * @throws IllegalArgumentException is <code>obj</code> is not a valid type.
239         */
240        @Override
241        public StringBuffer format(Object obj, StringBuffer toAppendTo,
242                                   FieldPosition pos) {
243    
244            if (obj instanceof RealVector) {
245                return format( (RealVector)obj, toAppendTo, pos);
246            }
247    
248            throw MathRuntimeException.createIllegalArgumentException(
249                  "cannot format a {0} instance as a real vector",
250                  obj.getClass().getName());
251    
252        }
253    
254        /**
255         * Parses a string to produce a {@link RealVector} object.
256         * @param source the string to parse
257         * @return the parsed {@link RealVector} object.
258         * @exception ParseException if the beginning of the specified string
259         *            cannot be parsed.
260         */
261        public ArrayRealVector parse(String source) throws ParseException {
262            ParsePosition parsePosition = new ParsePosition(0);
263            ArrayRealVector result = parse(source, parsePosition);
264            if (parsePosition.getIndex() == 0) {
265                throw MathRuntimeException.createParseException(
266                        parsePosition.getErrorIndex(),
267                        "unparseable real vector: \"{0}\"", source);
268            }
269            return result;
270        }
271    
272        /**
273         * Parses a string to produce a {@link RealVector} object.
274         * @param source the string to parse
275         * @param pos input/ouput parsing parameter.
276         * @return the parsed {@link RealVector} object.
277         */
278        public ArrayRealVector parse(String source, ParsePosition pos) {
279            int initialIndex = pos.getIndex();
280    
281            // parse prefix
282            parseAndIgnoreWhitespace(source, pos);
283            if (!parseFixedstring(source, trimmedPrefix, pos)) {
284                return null;
285            }
286    
287            // parse components
288            List<Number> components = new ArrayList<Number>();
289            for (boolean loop = true; loop;){
290    
291                if (!components.isEmpty()) {
292                    parseAndIgnoreWhitespace(source, pos);
293                    if (!parseFixedstring(source, trimmedSeparator, pos)) {
294                        loop = false;
295                    }
296                }
297    
298                if (loop) {
299                    parseAndIgnoreWhitespace(source, pos);
300                    Number component = parseNumber(source, format, pos);
301                    if (component != null) {
302                        components.add(component);
303                    } else {
304                        // invalid component
305                        // set index back to initial, error index should already be set
306                        pos.setIndex(initialIndex);
307                        return null;
308                    }
309                }
310    
311            }
312    
313            // parse suffix
314            parseAndIgnoreWhitespace(source, pos);
315            if (!parseFixedstring(source, trimmedSuffix, pos)) {
316                return null;
317            }
318    
319            // build vector
320            double[] data = new double[components.size()];
321            for (int i = 0; i < data.length; ++i) {
322                data[i] = components.get(i).doubleValue();
323            }
324            return new ArrayRealVector(data, false);
325    
326        }
327    
328        /**
329         * Parses a string to produce a object.
330         * @param source the string to parse
331         * @param pos input/ouput parsing parameter.
332         * @return the parsed object.
333         * @see java.text.Format#parseObject(java.lang.String, java.text.ParsePosition)
334         */
335        @Override
336        public Object parseObject(String source, ParsePosition pos) {
337            return parse(source, pos);
338        }
339    
340    }