Convert numbered pinyin to pinyin with tone marks

Question

Are there any scripts, libraries, or programs using Python, or BASH tools (e.g. awk, perl, sed) which can correc

Answer 1

Updated code: Careful that @Lakedaemon's Kotlin code doesn't contemplate the tone placement rules.

• A and e trump all other vowels and always take the tone mark. There are no Mandarin syllables in Hanyu Pinyin that contain both a and e.
• In the combination ou, o takes the mark.
• In all other cases, the final vowel takes the mark.

I originally ported @Lakedaemon's Kotlin code to Java, now I modified it and urge people who used this or @Lakedaemon's Kotlin code to update it.

I added an extra auxiliary function to get the correct tone mark postion.

    private static int getTonePosition(String r) {
        String lowerCase = r.toLowerCase();

        // exception to the rule
        if (lowerCase.equals("ou")) return 0;

        // higher precedence, both never go together
        int preferencePosition = lowerCase.indexOf('a');
        if (preferencePosition >= 0) return preferencePosition;
        preferencePosition = lowerCase.indexOf('e');
        if (preferencePosition >= 0) return preferencePosition;

        // otherwise the last one takes the tone mark
        return lowerCase.length() - 1;
    }

    static public String getCharacter(String string, int position) {
        char[] characters = string.toCharArray();
        return String.valueOf(characters[position]);
    }

    static public String toPinyin(String asciiPinyin) {
        Map pinyinToneMarks = new HashMap<>();
        pinyinToneMarks.put("a", "āáǎà"); pinyinToneMarks.put("e", "ēéěè");
        pinyinToneMarks.put("i", "īíǐì"); pinyinToneMarks.put("o",  "ōóǒò");
        pinyinToneMarks.put("u", "ūúǔù"); pinyinToneMarks.put("ü", "ǖǘǚǜ");
        pinyinToneMarks.put("A",  "ĀÁǍÀ"); pinyinToneMarks.put("E", "ĒÉĚÈ");
        pinyinToneMarks.put("I", "ĪÍǏÌ"); pinyinToneMarks.put("O", "ŌÓǑÒ");
        pinyinToneMarks.put("U", "ŪÚǓÙ"); pinyinToneMarks.put("Ü",  "ǕǗǙǛ");

        Pattern pattern = Pattern.compile("([aeiouüvÜ]{1,3})(n?g?r?)([012345])");
        Matcher matcher = pattern.matcher(asciiPinyin);
        StringBuilder s = new StringBuilder();
        int start = 0;

        while (matcher.find(start)) {
            s.append(asciiPinyin, start, matcher.start(1));
            int tone = Integer.parseInt(matcher.group(3)) % 5;
            String r = matcher.group(1).replace("v", "ü").replace("V", "Ü");
            if (tone != 0) {
                int pos = getTonePosition(r);
                s.append(r, 0, pos).append(getCharacter(pinyinToneMarks.get(getCharacter(r, pos)),tone - 1)).append(r, pos + 1, r.length());
            } else {
                s.append(r);
            }
            s.append(matcher.group(2));
            start = matcher.end(3);
        }
        if (start != asciiPinyin.length()) {
            s.append(asciiPinyin, start, asciiPinyin.length());
        }
        return s.toString();
    }