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Common TL

Prerequisite

  • Python >= 3.8

Usage examples

Convert a sentence written in Chinese characters to Common TL

A dictionary composed of tab-separated values is required, see Dictionary Preparation.

>>> import ch2rm, ctl_dict
>>> dict_ = ctl_dict.DictSrc().add_dict_src('dict_example/Ch2TwRoman.txt', (ctl_dict.TL, ctl_dict.Word, ctl_dict.ETC)).create_dict()
>>> sentence = ch2rm.chinese_to_roman('你是誰?', dict_)
>>> print(sentence)
[[('dl', 'i2')], [('sc', 'i7')], [('tsc', 'ia5')]]
>>> print(' '.join('-'.join(''.join(syll) for syll in word) for word in sentence))
dli2 sci7 tscia5

Convert a sentence written in TL to Common TL

Punctuation and capitalization are ignored.

>>> import ch2rm
>>> sentence = ch2rm.phonetic_to_tl("Thài-khong pîng-iú, lín hó! Lín tsia̍h-pá bē? Ū-îng, tō-lâi gún-tsia tsē--ooh.")
>>> print(sentence)
[[('th', 'ai3'), ('kh', 'oong1')], [('p', 'iong5'), ('', 'iu2')], [('dl', 'in2')], [('h', 'o2')], [('dl', 'in2')], [('tsc', 'iah8'), ('p', 'a2')], [('b', 'e7')], [('', 'u7'), ('', 'iong5')], [('t', 'o7'), ('dl', 'ai5')], [('g', 'un2'), ('tsc', 'ia1')], [('ts', 'e7'), ('', 'ooh0')]]
>>> print(' '.join('-'.join(''.join(syll) for syll in word) for word in sentence))
thai3-khoong1 piong5-iu2 dlin2 ho2 dlin2 tsciah8-pa2 be7 u7-iong5 to7-dlai5 gun2-tscia1 tse7-ooh0

Convert a string-form sentence in Bopomofo (Zhuyin) and TL into IPA or Common TL

String-form sentence means a Python list of string-form words. A string-form word is a Python list of a phonetic syllable. (Explained below)

Custom function definitions:

import ch2rm
import ctl_dict

def phonetic_sentence_to_ipa(sentence, phonetic=None):
     return [ch2rm.phonetic_word_to_ipa(word, phonetic=phonetic) for word in sentence]

def phonetic_sentence_to_ctl(sentence, phonetic=None):
     return [ch2rm.phonetic_word_to_tl(word, phonetic=phonetic) for word in sentence]

Execution (continued):

>>> TL = ctl_dict.TL
>>> Zhuyin = ctl_dict.Zhuyin
>>> sentence = [["ㄍㄢˇ", "ㄒㄧㄝˋ"], ["ㄍㄜˋ", "ㄨㄟˋ"], [TL("lâng"), TL("kheh")]]
>>> #            感謝                 各位               人客
>>> phonetic_sentence_to_ipa(sentence, phonetic=Zhuyin)
[[('k', 'an03'), ('ɕ', 'je04')], [('k', 'ɤ04'), ('', 'wei04')], [('ᵈl', 'aŋ5'), ('kʰ', 'eʔ4')]]
>>> phonetic_sentence_to_ctl(sentence, phonetic=Zhuyin)
[[('k', 'an03'), ('s', 'ie04')], [('k', 'o04'), ('', 'uei04')], [('dl', 'ang5'), ('kh', 'eh4')]]

Term Definitions/Concepts Used in This Project

Terms/Concepts about Phonetic Notation Systems

Common TL (CTL) (as a phonetic transcription system)

A phonetic transcription system based on modified Taiwanese Romanization System (TL).

CTL uses only ASCII symbols and can be used to transcribe some Chinese languages and dialects other than Taiwanese Hokkien.

Currently applicable Chinese languages and dialects:

  • Taiwanese Hokkien
    • Chiang-chiu and Chôan-chiu dialects are applicable.
  • Standard Mandarin
  • Taiwanese Hakka
    • Sixian, Hailu, Dabu, Raoping, Zhao'an, and Southern Sixian dialects are applicable.

The commonly used phonetic notations used by these languages and dialects can be converted into CTL and then be converted back without losing any information other than the following:

  • The citation tone of neutral tone syllables is lost for TL.
  • TL o vs. oo for variants of Taiwanese Hokkien where TL o is pronounced as [o] if the Southern transcription variant of CTL is used.

The strict form of CTL can also spells out non-phonemic features so that every grapheme at the same position within a syllable represents the same range of speech sound among all applicable language and dialects. This is the form used by this project.

CTL has two transcription variants as listed in the following table:

CTL Variant [ə] [o]~[ʊ] /ɔ/
Southern o oo oo
Northern or o oo

A phonetic transcription system based on the Latin script.

IPA uses non-ASCII symbols and diacritics to transcribe speech sounds.

In this project, a modified form of IPA is used, where the tone is represented by a number instead of IPA tone letters.

CTL can be converted into the modified form of IPA and be converted back without losing any information.

Syllable Component Definition

  • Initial: Initial
  • Final: Medial, nucleus, coda, and tone number

Reference for Typical Linguistic Syllable Component Definitions

Syllable forms (forms to represent a syllable)

  • String form: A str or an instance of _Phonetic (a subclass of UserString; see below)
  • Pair form: An initial-final pair (see below)

Initial-final pair (pair-form syllable)

A pair of an initial string and a final string in phonetic notation which represents a syllable
I.e., (initial, final)

An initial-final pair can also be one of …

  • IPA pair, if the initial and final are both in IPA (phonemic) notation, except that the tone is represented by a number instead of IPA tone letters. (typing hint: phonetic.phonetic.IpaPair)
  • CTL pair, if the initial and final are both in CTL. (typing hint: phonetic.phonetic.CtlPair)

Example:

Word IPA IPA, pair form TL, pair form
phing
(Taiwanese Hokkien, Kaohsiung)
/pʰiəŋ˥˥/ ('pʰ', 'iəŋ1') ('ph', 'ing1')

Word forms

  • Ordinarily written text
  • Phonetic string: A single string of the phonetic notation of the whole word.
  • String form: A list of string-form syllables of the word (typing hint: ch2rm.PhoneticSylList)
  • Pair form: A list of pair-form syllables of the word (typing hints: ch2rm.IpaWord & ch2rm.CtlWord)

Example:

Word IPA IPA, string form IPA, pair form
拼音 phing-im
(Taiwanese Hokkien, Kaohsiung)
/pʰiəŋ˥˥.im˥˥/ ['pʰiəŋ1', 'im1'] [('pʰ', 'iəŋ1'), ('', 'im1')]

Sentence forms

  • Ordinarily written text
  • Segmented written text: A list of ordinarily written words of the sentence
  • Phonetic string: A single string of the phonetic notation of the whole sentence.
  • String form: A list of string-form words of the sentence
  • Pair form: A list of pair-form words of the sentence

In the string form, each string-form word can have independent type (str or one of the subclasses of _Phonetic; see below)

Example:

Sentence Words TL, string form TL, pair form
咱人生來自由
Lán-lâng senn--lâi tsū-iû
(Taiwanese Hokkien, Kaohsiung)
咱人 lán-lâng,
生來 senn--lâi,
自由 tsū-iû
[['lan2', 'lang5'], ['senn1', 'lai0'], ['tsu7', 'iu5']] [[('l', 'an2'), ('l', 'ang5')], [('s', 'enn1'), ('l', 'ai0')], [('ts', 'u7'), ('', 'iu5')]]

Comparison of Text Forms

Form Sentence Word Syllable
Ordinarily written text Sentence text
& segmented text
Word text
Phonetic string Phonetic sentence (string) Phonetic word (string) Phonetic syllable
String form
(* of string(s))
String-form sentence (list of …) String-form word (list of …) Phonetic syllable
Pair form
(* of pair(s))
Pair-form sentence (list of …) Pair-form word (list of …) Initial-final pair

Note that:

  • There are no ordinarily written syllable texts. One-syllable texts are treated as one-word text.
  • There are no lists of phonetic word strings. However, a list of ordinarily written word texts can result from word segmentation.

Terms/Concepts about the Dictionary

Dictionary

typing hint: ctl_dict.CtlDict

A word-to-phonetic-notation dictionary built from any number of dictionary text files

Dictionary text file

A file composed of tab-separated values.

Each line in the file should be separated into $n$ fields by $n - 1$ tabs and should at least contains a Word field and a _Phonetic field

(pre-)processing (for dictionary text files)

  • Lines with XML escapes are ignored.
  • Fullwidth spaces are replaced with halfwidth spaces, and then successive spaces are reduced into a single space.
  • Character in parentheses are removed along with the parentheses.
  • Latin phonetic alphabet are normalized into NFD form.
  • Words with the syllable count not consistent with the phonetic notation are ignored.

Dictionary format specification

typing hint: ctl_dict.Format

A tuple of dictionary format tokens used for specifying the fields of a dictionary text file.

Dictionary format token

A set of subclass of UserString.

Current support format tokens (only those not prefixed with _ should be used):

  • Word: Field for the word
  • _Phonetic: Field for the word in phonetic notation (syllables are separated by spaces)
    Subclasses:
    • _RomanPhonetic: Phonetic notation systems using Latin alphabet
      • TaiwaneseRomanization (TL)
      • TaiwaneseHakkaRomanization (THRS)
    • Zhuyin
  • ETC: Ignored field

Dictionary text file specification item

typing hint: ctl_dict.SrcItem

Either a string of the path to a dictionary text file or a tuple with such a string and dictionary format specification.

Dictionary text file specification

typing hint: ctl_dict.SrcSpec

Either a list of (typing hint: ctl_dict.SrcList) or a single dictionary text file specification item.

Comparison of Dictionary Text File Specification Components

Component typing hint
(ctl_dict.*)
typing hint (partially expanded)
Dictionary format token Union[str, Type[UserString]]
Dictionary format specification Format Sequence[Union[str, Type[UserString]]]]
Dictionary text file specification item SrcItem Union[str, Tuple[str, Format]]
Dictionary text file specification SrcSpec Union[List[SrcItem], SrcItem]

Text Conversion Functions

These functions perform word segmentation and pronunciation querying and thus require the use of a dictionary, see Dictionary Preparation.

Word level (ordinarily written)

ch2rm.chinese_word_to_phonetic(word: str, dict_: ctl_dict.CtlDict) -> ctl_dict.DictPronounCandList

Return a list of the possible phonetic notations of the ordinarily written word in the dictionary dict_

Sentence level (ordinarily written)

ch2rm.chinese_to_roman(sentence: str, dict_: ctl_dict.CtlDict, dialects: Lang = ch2rm.lang()) -> List[CtlWord]

Segment the ordinarily written sentence into words, and then convert the result into a pair-form CTL sentence

Phonetic Notation Conversion Functions

These functions only perform conversions between phonetic notations and thus do not require the use of dictionaries.

Syllable level (string form)

phonetic.*.*_syllable_to_ipa(syll: Str, dialect: Optional[str] = ?, variant: Optional[str] = ?) -> IpaPair

Convert a syllable string syll written in the phonetic notation system * into an IPA pair

E.g.,

  • phonetic.tl.tl_syllable_to_ipa(tl_: Str, dialect: Optional[str] = 'chiang', variant: Optional[str] = 'southern') -> phonetic.IpaPair
    • Convert a Taiwanese Hokkien syllable written in TL syll into an IPA pair
  • phonetic.zhuyin.zhuyin_syllable_to_ipa(zhuyin: Str, dialect: Optional[str] = None, variant: Optional[str] = None) -> IpaPair
    • Convert a Standard Mandarin syllable written in Zhuyin/Bopomofo zhuyin into an IPA pair

Syllable level (pair form)

phonetic.common_tl.ipa_pair_to_tl_pair(ipa_pair: IpaPair, dialect: Optional[str] = None, variant: Optional[str] = 'southern') -> CtlPair

Convert an IPA pair into a CTL pair

Word level

ch2rm.phonetic_word_to_ipa(phonetic_word: PhoneticSylList, dialects: Lang = ch2rm.lang(), phonetic: Optional[Type[ctl_dict._Phonetic]] = None) -> IpaWord

Convert a string-form phonetic word into a pair-form IPA word

The phonetic notation system of each syllable is specified by its type (one of the subclasses of _Phonetic) or phonetic if its type is str.

ch2rm.ipa_pair_to_tl(ipa_pair: IpaWord, *args, **kwargs) -> CtlWord

Convert a pair-form IPA word into a pair-form CTL word

Its non-positional arguments are forwarded to phonetic.common_tl.ipa_pair_to_tl_pair().

ch2rm.phonetic_word_to_tl(phonetic_word: PhoneticSylList, dialects: Lang = ch2rm.lang(), phonetic: Optional[Type[ctl_dict._Phonetic]] = None) -> CtlWord

Convert a string-form word into a pair-form CTL word

This function is the combination of the previous two functions.

Sentence level (phonetic string)

ch2rm.phonetic_to_tl(sentence: str, dialects: Lang = ch2rm.lang(), phonetic: Type[ctl_dict._Phonetic] = ctl_dict.TL) -> List[CtlWord]

Segment the TL-like phonetic sentence into words, and then convert the result into a pair-form CTL sentence

Comparison of Conversion Functions

To→
From↓
Phonetic *
(string-form)
IPA *
(pair-form)
CTL *
(pair-form)
Ordinarily written
(chinese_word_to_phonetic())
chinese_to_roman()
 
Phonetic string phonetic_to_tl()
 
Phonetic *
(string-form)

phonetic_word_to_ipa()
*_syllable_to_ipa()

phonetic_word_to_tl()
 
IPA *
(pair-form)

ipa_pair_to_tl()
ipa_pair_to_tl_pair()

Note that:

  • chinese_word_to_phonetic() returns a list of string-form words, which resembles a string-form sentence but every syllable is ensured to be of a subtype of _Phonetic. The return value is treated as in the word level and has the typing hint ctl_dict.DictPronounCandList.
  • There are no other conversion functions which directly convert texts from a level (sentence/word/syllable) to another.

Dialect-specifying arguments

Except for chinese_word_to_phonetic(), all sentence-level and word-level conversion functions accept an optional argument dialects (typing hint: Lang) for specifying the (sub-)dialect for each applicable language/dialect. Its default value is equivalent to:

ch2rm.lang(
    hokkien=ch2rm.lang_opt(dialect='chiang', variant='southern'),
    mandarin=ch2rm.lang_opt(dialect=None, variant=None),
    hakka=ch2rm.lang_opt(dialect='sixian', variant=None),
    common_tl=ch2rm.lang_opt(dialect=None, variant='southern'))

All arguments of ch2rm.lang() and ch2rm.lang_opt() are optional. All arguments of ch2rm.lang_opt() can be positional.

Expected combinations of arguments to ch2rm.lang() are listed in the following table:

Keyword Language/Dialect (dialect, variant) Valid *
hokkien Taiwanese Hokkien ('chiang', *)
('choan', *)
'southern'
'northern'
mandarin Standard Mandarin (None, None)
hakka Taiwanese Hakka ('sixian', None)
('hailu', None)
('dabu', None)
('raoping', 'hsinchu')
('raoping', 'zhuolan')
('zhao_an', None)
('southern_sixian', None)
common_tl (For choosing CTL variant) (None, *) 'southern'
'northern'

For choosing CTL variant, if the argument common_tl is omitted, the argument hokkien is used if provided.

For syllable-level conversion functions, the arguments dialect and variant can be used for specifying the (sub-)dialect. See the above table for expected combinations of dialect and variant.

Word Segmentation Functions

These functions require the use of a dictionary, see Dictionary Preparation.

String level

ctl_segment.split_chinese_word(sentence: str, dict_: ctl_dict.CtlDict) -> List[str]

Segment the ordinarily written sentence into words. Currently, the forward maximum matching algorithm is used.

Before the segmentation, the spaces within sentence are reduced to 1 space between TL-like words and removed otherwise.

File level

ctl_segment.split_file(path: str, dict_: ctl_dict.CtlDict) -> None

Perform word segmentation for the first line of the .trn file at path in-place

A backup file whose path is _bk suffixed to the original path is created.

Directory level

ctl_segment.split_for_each_file(path: str, dict_: ctl_dict.CtlDict) -> None

Perform word segmentation for the first line of all .trn files under path and its all (direct or indirect) sub-directories in-place

It calls ctl_segment.split_file() and thus also creates backup files.

Dictionary Functions

These functions are used to create a CtlDict object.

Module functions

ctl_dict.create_dict(path_list: SrcList, *args, **kwargs) -> CtlDict

Create a dictionary using the given dictionary text file specification

A ctl_dict.DictSrc object is created internally.

Dictionary Builder Methods

These are methods of the class ctl_dict.DictSrc.

DictSrc.add_dict_src(self, path: str, format_: Format)

Add the given dictionary text file with given format specification into the dictionary text file specification

DictSrc.reset_dict_src(self)

Clear the dictionary text file specification

DictSrc.set_dict_src(self, path_list: SrcSpec)

Specify the dictionary text file specification

DictSrc.create_dict(self, reprocess: bool = False, recreate_dump: bool = False) -> CtlDict

Create a dictionary. All the specified dictionary text files are separately loaded and dumped and then combined in-order and dumped again. By default, the already dumped data are loaded if exist.

Dictionary Preparation

A dictionary is required only when text segmentation or pronunciation querying is needed.

The dictionary text files under dict_example/ are minimal examples which merely sufficient to demonstrate these functionalities.

For practical use, it is viable to use the dictionary data from the online dictionaries compiled by the Ministry of Education of Taiwan. The already released dictionary data should be used.

Get Released Dictionary Data

Among these online dictionaries, the following ones are recommended to use and their released data are available:

Convert Dictionary Data

To allow these dictionary data files to be read into a CtlDict object, these files should be converted into tab-separated values.

There are many tools available for such conversion. which are not covered here.

The converted dictionary text files should be able to be loaded into a CtlDict object by using suitable dictionary text file specifications.

About

A tool that aims at converting Taiwanese Hokkien sentences written in Chinese characters to phonetic words.

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