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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.complex;
import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;
import java.util.Locale;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.MathParseException;
import org.apache.commons.math3.exception.NoDataException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.util.CompositeFormat;
/**
* Formats a Complex number in cartesian format "Re(c) + Im(c)i". 'i' can
* be replaced with 'j' (or anything else), and the number format for both real
* and imaginary parts can be configured.
*
*/
public class ComplexFormat {
/** The default imaginary character. */
private static final String DEFAULT_IMAGINARY_CHARACTER = "i";
/** The notation used to signify the imaginary part of the complex number. */
private final String imaginaryCharacter;
/** The format used for the imaginary part. */
private final NumberFormat imaginaryFormat;
/** The format used for the real part. */
private final NumberFormat realFormat;
/**
* Create an instance with the default imaginary character, 'i', and the
* default number format for both real and imaginary parts.
*/
public ComplexFormat() {
this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
this.imaginaryFormat = CompositeFormat.getDefaultNumberFormat();
this.realFormat = imaginaryFormat;
}
/**
* Create an instance with a custom number format for both real and
* imaginary parts.
* @param format the custom format for both real and imaginary parts.
* @throws NullArgumentException if {@code realFormat} is {@code null}.
*/
public ComplexFormat(NumberFormat format) throws NullArgumentException {
if (format == null) {
throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
}
this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
this.imaginaryFormat = format;
this.realFormat = format;
}
/**
* Create an instance with a custom number format for the real part and a
* custom number format for the imaginary part.
* @param realFormat the custom format for the real part.
* @param imaginaryFormat the custom format for the imaginary part.
* @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
* @throws NullArgumentException if {@code realFormat} is {@code null}.
*/
public ComplexFormat(NumberFormat realFormat, NumberFormat imaginaryFormat)
throws NullArgumentException {
if (imaginaryFormat == null) {
throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
}
if (realFormat == null) {
throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
}
this.imaginaryCharacter = DEFAULT_IMAGINARY_CHARACTER;
this.imaginaryFormat = imaginaryFormat;
this.realFormat = realFormat;
}
/**
* Create an instance with a custom imaginary character, and the default
* number format for both real and imaginary parts.
* @param imaginaryCharacter The custom imaginary character.
* @throws NullArgumentException if {@code imaginaryCharacter} is
* {@code null}.
* @throws NoDataException if {@code imaginaryCharacter} is an
* empty string.
*/
public ComplexFormat(String imaginaryCharacter)
throws NullArgumentException, NoDataException {
this(imaginaryCharacter, CompositeFormat.getDefaultNumberFormat());
}
/**
* Create an instance with a custom imaginary character, and a custom number
* format for both real and imaginary parts.
* @param imaginaryCharacter The custom imaginary character.
* @param format the custom format for both real and imaginary parts.
* @throws NullArgumentException if {@code imaginaryCharacter} is
* {@code null}.
* @throws NoDataException if {@code imaginaryCharacter} is an
* empty string.
* @throws NullArgumentException if {@code format} is {@code null}.
*/
public ComplexFormat(String imaginaryCharacter, NumberFormat format)
throws NullArgumentException, NoDataException {
this(imaginaryCharacter, format, format);
}
/**
* Create an instance with a custom imaginary character, a custom number
* format for the real part, and a custom number format for the imaginary
* part.
*
* @param imaginaryCharacter The custom imaginary character.
* @param realFormat the custom format for the real part.
* @param imaginaryFormat the custom format for the imaginary part.
* @throws NullArgumentException if {@code imaginaryCharacter} is
* {@code null}.
* @throws NoDataException if {@code imaginaryCharacter} is an
* empty string.
* @throws NullArgumentException if {@code imaginaryFormat} is {@code null}.
* @throws NullArgumentException if {@code realFormat} is {@code null}.
*/
public ComplexFormat(String imaginaryCharacter,
NumberFormat realFormat,
NumberFormat imaginaryFormat)
throws NullArgumentException, NoDataException {
if (imaginaryCharacter == null) {
throw new NullArgumentException();
}
if (imaginaryCharacter.length() == 0) {
throw new NoDataException();
}
if (imaginaryFormat == null) {
throw new NullArgumentException(LocalizedFormats.IMAGINARY_FORMAT);
}
if (realFormat == null) {
throw new NullArgumentException(LocalizedFormats.REAL_FORMAT);
}
this.imaginaryCharacter = imaginaryCharacter;
this.imaginaryFormat = imaginaryFormat;
this.realFormat = realFormat;
}
/**
* Get the set of locales for which complex formats are available.
* This is the same set as the {@link NumberFormat} set.
* @return available complex format locales.
*/
public static Locale[] getAvailableLocales() {
return NumberFormat.getAvailableLocales();
}
/**
* This method calls {@link #format(Object,StringBuffer,FieldPosition)}.
*
* @param c Complex object to format.
* @return A formatted number in the form "Re(c) + Im(c)i".
*/
public String format(Complex c) {
return format(c, new StringBuffer(), new FieldPosition(0)).toString();
}
/**
* This method calls {@link #format(Object,StringBuffer,FieldPosition)}.
*
* @param c Double object to format.
* @return A formatted number.
*/
public String format(Double c) {
return format(new Complex(c, 0), new StringBuffer(), new FieldPosition(0)).toString();
}
/**
* Formats a {@link Complex} object to produce a string.
*
* @param complex 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(Complex complex, StringBuffer toAppendTo,
FieldPosition pos) {
pos.setBeginIndex(0);
pos.setEndIndex(0);
// format real
double re = complex.getReal();
CompositeFormat.formatDouble(re, getRealFormat(), toAppendTo, pos);
// format sign and imaginary
double im = complex.getImaginary();
StringBuffer imAppendTo;
if (im < 0.0) {
toAppendTo.append(" - ");
imAppendTo = formatImaginary(-im, new StringBuffer(), pos);
toAppendTo.append(imAppendTo);
toAppendTo.append(getImaginaryCharacter());
} else if (im > 0.0 || Double.isNaN(im)) {
toAppendTo.append(" + ");
imAppendTo = formatImaginary(im, new StringBuffer(), pos);
toAppendTo.append(imAppendTo);
toAppendTo.append(getImaginaryCharacter());
}
return toAppendTo;
}
/**
* Format the absolute value of the imaginary part.
*
* @param absIm Absolute value of the imaginary part of a complex number.
* @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.
*/
private StringBuffer formatImaginary(double absIm,
StringBuffer toAppendTo,
FieldPosition pos) {
pos.setBeginIndex(0);
pos.setEndIndex(0);
CompositeFormat.formatDouble(absIm, getImaginaryFormat(), toAppendTo, pos);
if (toAppendTo.toString().equals("1")) {
// Remove the character "1" if it is the only one.
toAppendTo.setLength(0);
}
return toAppendTo;
}
/**
* Formats a object to produce a string. {@code obj} must be either a
* {@link Complex} object or a {@link Number} object. Any other type of
* object will result in an {@link IllegalArgumentException} being thrown.
*
* @param obj 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.
* @see java.text.Format#format(java.lang.Object, java.lang.StringBuffer, java.text.FieldPosition)
* @throws MathIllegalArgumentException is {@code obj} is not a valid type.
*/
public StringBuffer format(Object obj, StringBuffer toAppendTo,
FieldPosition pos)
throws MathIllegalArgumentException {
StringBuffer ret = null;
if (obj instanceof Complex) {
ret = format( (Complex)obj, toAppendTo, pos);
} else if (obj instanceof Number) {
ret = format(new Complex(((Number)obj).doubleValue(), 0.0),
toAppendTo, pos);
} else {
throw new MathIllegalArgumentException(LocalizedFormats.CANNOT_FORMAT_INSTANCE_AS_COMPLEX,
obj.getClass().getName());
}
return ret;
}
/**
* Access the imaginaryCharacter.
* @return the imaginaryCharacter.
*/
public String getImaginaryCharacter() {
return imaginaryCharacter;
}
/**
* Access the imaginaryFormat.
* @return the imaginaryFormat.
*/
public NumberFormat getImaginaryFormat() {
return imaginaryFormat;
}
/**
* Returns the default complex format for the current locale.
* @return the default complex format.
*/
public static ComplexFormat getInstance() {
return getInstance(Locale.getDefault());
}
/**
* Returns the default complex format for the given locale.
* @param locale the specific locale used by the format.
* @return the complex format specific to the given locale.
*/
public static ComplexFormat getInstance(Locale locale) {
NumberFormat f = CompositeFormat.getDefaultNumberFormat(locale);
return new ComplexFormat(f);
}
/**
* Returns the default complex format for the given locale.
* @param locale the specific locale used by the format.
* @param imaginaryCharacter Imaginary character.
* @return the complex format specific to the given locale.
* @throws NullArgumentException if {@code imaginaryCharacter} is
* {@code null}.
* @throws NoDataException if {@code imaginaryCharacter} is an
* empty string.
*/
public static ComplexFormat getInstance(String imaginaryCharacter, Locale locale)
throws NullArgumentException, NoDataException {
NumberFormat f = CompositeFormat.getDefaultNumberFormat(locale);
return new ComplexFormat(imaginaryCharacter, f);
}
/**
* Access the realFormat.
* @return the realFormat.
*/
public NumberFormat getRealFormat() {
return realFormat;
}
/**
* Parses a string to produce a {@link Complex} object.
*
* @param source the string to parse.
* @return the parsed {@link Complex} object.
* @throws MathParseException if the beginning of the specified string
* cannot be parsed.
*/
public Complex parse(String source) throws MathParseException {
ParsePosition parsePosition = new ParsePosition(0);
Complex result = parse(source, parsePosition);
if (parsePosition.getIndex() == 0) {
throw new MathParseException(source,
parsePosition.getErrorIndex(),
Complex.class);
}
return result;
}
/**
* Parses a string to produce a {@link Complex} object.
*
* @param source the string to parse
* @param pos input/ouput parsing parameter.
* @return the parsed {@link Complex} object.
*/
public Complex parse(String source, ParsePosition pos) {
int initialIndex = pos.getIndex();
// parse whitespace
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
// parse real
Number re = CompositeFormat.parseNumber(source, getRealFormat(), pos);
if (re == null) {
// invalid real number
// set index back to initial, error index should already be set
pos.setIndex(initialIndex);
return null;
}
// parse sign
int startIndex = pos.getIndex();
char c = CompositeFormat.parseNextCharacter(source, pos);
int sign = 0;
switch (c) {
case 0 :
// no sign
// return real only complex number
return new Complex(re.doubleValue(), 0.0);
case '-' :
sign = -1;
break;
case '+' :
sign = 1;
break;
default :
// invalid sign
// set index back to initial, error index should be the last
// character examined.
pos.setIndex(initialIndex);
pos.setErrorIndex(startIndex);
return null;
}
// parse whitespace
CompositeFormat.parseAndIgnoreWhitespace(source, pos);
// parse imaginary
Number im = CompositeFormat.parseNumber(source, getRealFormat(), pos);
if (im == null) {
// invalid imaginary number
// set index back to initial, error index should already be set
pos.setIndex(initialIndex);
return null;
}
// parse imaginary character
if (!CompositeFormat.parseFixedstring(source, getImaginaryCharacter(), pos)) {
return null;
}
return new Complex(re.doubleValue(), im.doubleValue() * sign);
}
}