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With inspiration from other libraries
/*
* 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.commons.math3.linear;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import org.apache.commons.math3.exception.MathParseException;
import org.apache.commons.math3.util.CompositeFormat;
/**
* Formats a vector in components list format "{v0; v1; ...; vk-1}".
* The prefix and suffix "{" and "}" and the separator "; " can be replaced by
* any user-defined strings. The number format for components can be configured.
* White space is ignored at parse time, even if it is in the prefix, suffix
* or separator specifications. So even if the default separator does include a space
* character that is used at format time, both input string "{1;1;1}" and
* " { 1 ; 1 ; 1 } " will be parsed without error and the same vector will be
* returned. In the second case, however, the parse position after parsing will be
* just after the closing curly brace, i.e. just before the trailing space.
*
* @since 2.0
*/
public class RealVectorFormat {
/** The default prefix: "{". */
private static final String DEFAULT_PREFIX = "{";
/** The default suffix: "}". */
private static final String DEFAULT_SUFFIX = "}";
/** The default separator: ", ". */
private static final String DEFAULT_SEPARATOR = "; ";
/** Prefix. */
private final String prefix;
/** Suffix. */
private final String suffix;
/** Separator. */
private final String separator;
/** Trimmed prefix. */
private final String trimmedPrefix;
/** Trimmed suffix. */
private final String trimmedSuffix;
/** Trimmed separator. */
private final String trimmedSeparator;
/** The format used for components. */
private final NumberFormat format;
/**
* Create an instance with default settings.
* The instance uses the default prefix, suffix and separator:
* "{", "}", and "; " and the default number format for components.
*/
public RealVectorFormat() {
this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR,
CompositeFormat.getDefaultNumberFormat());
}
/**
* Create an instance with a custom number format for components.
* @param format the custom format for components.
*/
public RealVectorFormat(final NumberFormat format) {
this(DEFAULT_PREFIX, DEFAULT_SUFFIX, DEFAULT_SEPARATOR, format);
}
/**
* Create an instance with custom prefix, suffix and separator.
* @param prefix prefix to use instead of the default "{"
* @param suffix suffix to use instead of the default "}"
* @param separator separator to use instead of the default "; "
*/
public RealVectorFormat(final String prefix, final String suffix,
final String separator) {
this(prefix, suffix, separator,
CompositeFormat.getDefaultNumberFormat());
}
/**
* Create an instance with custom prefix, suffix, separator and format
* for components.
* @param prefix prefix to use instead of the default "{"
* @param suffix suffix to use instead of the default "}"
* @param separator separator to use instead of the default "; "
* @param format the custom format for components.
*/
public RealVectorFormat(final String prefix, final String suffix,
final String separator, final NumberFormat format) {
this.prefix = prefix;
this.suffix = suffix;
this.separator = separator;
trimmedPrefix = prefix.trim();
trimmedSuffix = suffix.trim();
trimmedSeparator = separator.trim();
this.format = format;
}
/**
* Get the set of locales for which real vectors formats are available.
* This is the same set as the {@link NumberFormat} set.
* @return available real vector format locales.
*/
public static Locale[] getAvailableLocales() {
return NumberFormat.getAvailableLocales();
}
/**
* Get the format prefix.
* @return format prefix.
*/
public String getPrefix() {
return prefix;
}
/**
* Get the format suffix.
* @return format suffix.
*/
public String getSuffix() {
return suffix;
}
/**
* Get the format separator between components.
* @return format separator.
*/
public String getSeparator() {
return separator;
}
/**
* Get the components format.
* @return components format.
*/
public NumberFormat getFormat() {
return format;
}
/**
* Returns the default real vector format for the current locale.
* @return the default real vector format.
*/
public static RealVectorFormat getInstance() {
return getInstance(Locale.getDefault());
}
/**
* Returns the default real vector format for the given locale.
* @param locale the specific locale used by the format.
* @return the real vector format specific to the given locale.
*/
public static RealVectorFormat getInstance(final Locale locale) {
return new RealVectorFormat(CompositeFormat.getDefaultNumberFormat(locale));
}
/**
* This method calls {@link #format(RealVector,StringBuffer,FieldPosition)}.
*
* @param v RealVector object to format.
* @return a formatted vector.
*/
public String format(RealVector v) {
return format(v, new StringBuffer(), new FieldPosition(0)).toString();
}
/**
* Formats a {@link RealVector} object to produce a string.
* @param vector the object to format.
* @param toAppendTo where the text is to be appended
* @param pos On input: an alignment field, if desired. On output: the
* offsets of the alignment field
* @return the value passed in as toAppendTo.
*/
public StringBuffer format(RealVector vector, StringBuffer toAppendTo,
FieldPosition pos) {
pos.setBeginIndex(0);
pos.setEndIndex(0);
// format prefix
toAppendTo.append(prefix);
// format components
for (int i = 0; i < vector.getDimension(); ++i) {
if (i > 0) {
toAppendTo.append(separator);
}
CompositeFormat.formatDouble(vector.getEntry(i), format, toAppendTo, pos);
}
// format suffix
toAppendTo.append(suffix);
return toAppendTo;
}
/**
* Parse a string to produce a {@link RealVector} object.
*
* @param source String to parse.
* @return the parsed {@link RealVector} object.
* @throws MathParseException if the beginning of the specified string
* cannot be parsed.
*/
public ArrayRealVector parse(String source) {
final ParsePosition parsePosition = new ParsePosition(0);
final ArrayRealVector result = parse(source, parsePosition);
if (parsePosition.getIndex() == 0) {
throw new MathParseException(source,
parsePosition.getErrorIndex(),
ArrayRealVector.class);
}
return result;
}
/**
* Parse a string to produce a {@link RealVector} object.
*
* @param source String to parse.
* @param pos input/ouput parsing parameter.
* @return the parsed {@link RealVector} object.
*/
public ArrayRealVector parse(String source, ParsePosition pos) {
int initialIndex = pos.getIndex();
// parse prefix
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
if (!CompositeFormat.parseFixedstring(source, trimmedPrefix, pos)) {
return null;
}
// parse components
List components = new ArrayList();
for (boolean loop = true; loop;){
if (!components.isEmpty()) {
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
if (!CompositeFormat.parseFixedstring(source, trimmedSeparator, pos)) {
loop = false;
}
}
if (loop) {
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
Number component = CompositeFormat.parseNumber(source, format, pos);
if (component != null) {
components.add(component);
} else {
// invalid component
// set index back to initial, error index should already be set
pos.setIndex(initialIndex);
return null;
}
}
}
// parse suffix
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
if (!CompositeFormat.parseFixedstring(source, trimmedSuffix, pos)) {
return null;
}
// build vector
double[] data = new double[components.size()];
for (int i = 0; i < data.length; ++i) {
data[i] = components.get(i).doubleValue();
}
return new ArrayRealVector(data, false);
}
}