[java] Converting Symbols, Accent Letters to English Alphabet

The problem is that, as you know, there are thousands of characters in the Unicode chart and I want to convert all the similar characters to the letters which are in English alphabet.

For instance here are a few conversions:

?->H
?->V
?->Y
O->O
?->C
t?? T???ly --> the Family
...

and I saw that there are more than 20 versions of letter A/a. and I don't know how to classify them. They look like needles in the haystack.

The complete list of unicode chars is at http://www.ssec.wisc.edu/~tomw/java/unicode.html or http://unicode.org/charts/charindex.html . Just try scrolling down and see the variations of letters.

How can I convert all these with Java? Please help me :(

I'm late to the party, but after facing this issue today, I found this answer to be very good:

String asciiName = Normalizer.normalize(unicodeName, Normalizer.Form.NFD)
    .replaceAll("[^\\p{ASCII}]", "");

Reference: https://stackoverflow.com/a/16283863

It's a part of Apache Commons Lang as of ver. 3.0.

org.apache.commons.lang3.StringUtils.stripAccents("Añ");

returns An

Also see http://www.drillio.com/en/software-development/java/removing-accents-diacritics-in-any-language/

There is no easy or general way to do what you want because it is just your subjective opinion that these letters look loke the latin letters you want to convert to. They are actually separate letters with their own distinct names and sounds which just happen to superficially look like a latin letter.

If you want that conversion, you have to create your own translation table based on what latin letters you think the non-latin letters should be converted to.

(If you only want to remove diacritial marks, there are some answers in this thread: How do I remove diacritics (accents) from a string in .NET? However you describe a more general problem)

The problem with "converting" arbitrary Unicode to ASCII is that the meaning of a character is culture-dependent. For example, “ß” to a German-speaking person should be converted to "ss" while an English-speaker would probably convert it to “B”.

Add to that the fact that Unicode has multiple code points for the same glyphs.

The upshot is that the only way to do this is create a massive table with each Unicode character and the ASCII character you want to convert it to. You can take a shortcut by normalizing characters with accents to normalization form KD, but not all characters normalize to ASCII. In addition, Unicode does not define which parts of a glyph are "accents".

Here is a tiny excerpt from an app that does this:

switch (c)
{
    case 'A':
    case '\u00C0':  //  À LATIN CAPITAL LETTER A WITH GRAVE
    case '\u00C1':  //  Á LATIN CAPITAL LETTER A WITH ACUTE
    case '\u00C2':  //  Â LATIN CAPITAL LETTER A WITH CIRCUMFLEX
    // and so on for about 20 lines...
        return "A";
        break;

    case '\u00C6'://  Æ LATIN CAPITAL LIGATURE AE
        return "AE";
        break;

    // And so on for pages...
}

Following Class does the trick:

org.apache.lucene.analysis.miscellaneous.ASCIIFoldingFilter

String tested : ÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝß

Tested :

• Output from Apache Commons Lang3 : AAAAAÆCEEEEIIIIÐNOOOOOØUUUUYß
• Output from ICU4j : AAAAAÆCEEEEIIIIÐNOOOOOØUUUUYß
• Output from JUnidecode : AAAAAAECEEEEIIIIDNOOOOOOUUUUUss (problem with Ý and another issue)
• Output from Unidecode : AAAAAAECEEEEIIIIDNOOOOOOUUUUYss

The last choice is the best.

The original request has been answered already.

However, I am posting the below answer for those who might be looking for generic transliteration code to transliterate any charset to Latin/English in Java.

Naive meaning of tranliteration: Translated string in it's final form/target charset sounds like the string in it's original form. If we want to transliterate any charset to Latin(English alphabets), then ICU4(ICU4J library in java ) will do the job.

Here is the code snippet in java:

    import com.ibm.icu.text.Transliterator; //ICU4J library import

    public static String TRANSLITERATE_ID = "NFD; Any-Latin; NFC";
    public static String NORMALIZE_ID = "NFD; [:Nonspacing Mark:] Remove; NFC";

    /**
    * Returns the transliterated string to convert any charset to latin.
    */
    public static String transliterate(String input) {
        Transliterator transliterator = Transliterator.getInstance(TRANSLITERATE_ID + "; " + NORMALIZE_ID);
        String result = transliterator.transliterate(input);
        return result;
    }

Attempting to "convert them all" is the wrong approach to the problem.

Firstly, you need to understand the limitations of what you are trying to do. As others have pointed out, diacritics are there for a reason: they are essentially unique letters in the alphabet of that language with their own meaning / sound etc.: removing those marks is just the same as replacing random letters in an English word. This is before you even go onto consider the Cyrillic languages and other script based texts such as Arabic, which simply cannot be "converted" to English.

If you must, for whatever reason, convert characters, then the only sensible way to approach this it to firstly reduce the scope of the task at hand. Consider the source of the input - if you are coding an application for "the Western world" (to use as good a phrase as any), it would be unlikely that you would ever need to parse Arabic characters. Similarly, the Unicode character set contains hundreds of mathematical and pictorial symbols: there is no (easy) way for users to directly enter these, so you can assume they can be ignored.

By taking these logical steps you can reduce the number of possible characters to parse to the point where a dictionary based lookup / replace operation is feasible. It then becomes a small amount of slightly boring work creating the dictionaries, and a trivial task to perform the replacement. If your language supports native Unicode characters (as Java does) and optimises static structures correctly, such find and replaces tend to be blindingly quick.

This comes from experience of having worked on an application that was required to allow end users to search bibliographic data that included diacritic characters. The lookup arrays (as it was in our case) took perhaps 1 man day to produce, to cover all diacritic marks for all Western European languages.

If the need is to convert "òéisöç->oeisoc", you can use this a starting point :

public class AsciiUtils {
    private static final String PLAIN_ASCII =
      "AaEeIiOoUu"    // grave
    + "AaEeIiOoUuYy"  // acute
    + "AaEeIiOoUuYy"  // circumflex
    + "AaOoNn"        // tilde
    + "AaEeIiOoUuYy"  // umlaut
    + "Aa"            // ring
    + "Cc"            // cedilla
    + "OoUu"          // double acute
    ;

    private static final String UNICODE =
     "\u00C0\u00E0\u00C8\u00E8\u00CC\u00EC\u00D2\u00F2\u00D9\u00F9"             
    + "\u00C1\u00E1\u00C9\u00E9\u00CD\u00ED\u00D3\u00F3\u00DA\u00FA\u00DD\u00FD" 
    + "\u00C2\u00E2\u00CA\u00EA\u00CE\u00EE\u00D4\u00F4\u00DB\u00FB\u0176\u0177" 
    + "\u00C3\u00E3\u00D5\u00F5\u00D1\u00F1"
    + "\u00C4\u00E4\u00CB\u00EB\u00CF\u00EF\u00D6\u00F6\u00DC\u00FC\u0178\u00FF" 
    + "\u00C5\u00E5"                                                             
    + "\u00C7\u00E7" 
    + "\u0150\u0151\u0170\u0171" 
    ;

    // private constructor, can't be instanciated!
    private AsciiUtils() { }

    // remove accentued from a string and replace with ascii equivalent
    public static String convertNonAscii(String s) {
       if (s == null) return null;
       StringBuilder sb = new StringBuilder();
       int n = s.length();
       for (int i = 0; i < n; i++) {
          char c = s.charAt(i);
          int pos = UNICODE.indexOf(c);
          if (pos > -1){
              sb.append(PLAIN_ASCII.charAt(pos));
          }
          else {
              sb.append(c);
          }
       }
       return sb.toString();
    }

    public static void main(String args[]) {
       String s = 
         "The result : È,É,Ê,Ë,Û,Ù,Ï,Î,À,Â,Ô,è,é,ê,ë,û,ù,ï,î,à,â,ô,ç";
       System.out.println(AsciiUtils.convertNonAscii(s));
       // output : 
       // The result : E,E,E,E,U,U,I,I,A,A,O,e,e,e,e,u,u,i,i,a,a,o,c
    }
}

The JDK 1.6 provides the java.text.Normalizer class that can be used for this task.

See an example here

You could try using unidecode, which is available as a ruby gem and as a perl module on cpan. Essentially, it works as a huge lookup table, where each unicode code point relates to an ascii character or string.

Since the encoding that turns "the Family" into "t?? T???ly" is effectively random and not following any algorithm that can be explained by the information of the Unicode codepoints involved, there's no general way to solve this algorithmically.

You will need to build the mapping of Unicode characters into latin characters which they resemble. You could probably do this with some smart machine learning on the actual glyphs representing the Unicode codepoints. But I think the effort for this would be greater than manually building that mapping. Especially if you have a good amount of examples from which you can build your mapping.

To clarify: a few of the substitutions can actually be solved via the Unicode data (as the other answers demonstrate), but some letters simply have no reasonable association with the latin characters which they resemble.

Examples:

• "?" (U+0452 CYRILLIC SMALL LETTER DJE) is more related to "d" than to "h", but is used to represent "h".
• "T" (U+0166 LATIN CAPITAL LETTER T WITH STROKE) is somewhat related to "T" (as the name suggests) but is used to represent "F".
• "?" (U+0E04 THAI CHARACTER KHO KHWAI) is not related to any latin character at all and in your example is used to represent "a"