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I'm working on string manipulation in Python (v3.3), and I'm wondering if there's a predictable way to detect the addition of diacritical markings on a given character.

So for instance is there some relationship between 'α' # ord('α') = 945) (Greek unmarked alpha) and 'ᾶ' # ord('ᾶ') = 8118 (Greek alpha with a circumflex) and 'ω' # ord('ω') = 969 (Greek unmarked omega) and 'ῶ' # ord('ῶ') = 8182 (Greek omega with a circumflex)?

Are there any manipulations that can be done to clear the diacritics? Or to add a diacritic, for example when marking a long vowel: 'ᾱ' # ord('ᾱ') = 8113?

Thanks!

Edit: I've played around with both the unidecode package and unicodedata. I'm not looking simply to normalize strings; I'm interested in resources for understanding the byte manipulations that happen behind the scenes to add, say, a circumflex or a macron to a standard alpha. Another way of asking that question is how does chr(945) # 'α' become or relate to chr(8113) # 'ᾱ' at a very low level? Maybe I'm thinking of this (text) in completely the wrong way, and I'd be interested in learning that too.

This question doesn't actually have so much to do with Python as it does with text encoding in general, but I mention Python just in case any of its peculiarities come into play.

Edit 2: I should also add that I'm more interested in how something like unidecode works than in actually using it at the moment. unidecode('ῶ') and unidecode('ὄ') # that's an omicron, not an 'o' both return 'o', and that return value isn't as helpful to me at the moment as a higher-level understanding of how the unidecode module arrives at that return value.

Philoktetes
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    You probably want to look into Unicode string *normalization*. Beyond that, I think the question is a little too vague still. – Karl Knechtel Dec 08 '13 at 20:17
  • http://stackoverflow.com/questions/517923/what-is-the-best-way-to-remove-accents-in-a-python-unicode-string – NPE Dec 08 '13 at 20:18
  • also http://stackoverflow.com/questions/4162603/python-and-character-normalization – NPE Dec 08 '13 at 20:19
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    unidecode is basically a big lookup table. – Simeon Visser Dec 08 '13 at 20:49
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    There are no logical relations between unaccented characters, accents, and accented characters in Unicode. The codepoint tables are created by demand (= what are people using). Any decomposition boils down to copying the relevant data from http://www.unicode.org and converting it to accessible data. – Jongware Dec 08 '13 at 21:02
  • @SimeonVisser @Jongware Got it, thanks. That was my hunch after reading through everything I could find (including the source for `unidecode`) but I thought I would ask on here in case I was missing something. – Philoktetes Dec 08 '13 at 21:24

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As @Jongware and @SimeonVisser pointed out, "Unicode is basically just a big lookup table," so there's secret sauce along the lines of what I was looking for.

Marking as answered--hopefully the directness here will help someone with a similar question in the future.

Philoktetes
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    Just stumbled upon this [Unicode/UTF8](http://stackoverflow.com/questions/313555/light-c-unicode-library) question, and the [utf8proc](http://www.flexiguided.de/publications.utf8proc.en.html) suggested may be something worth checking out. Its features include decomposition and normalization, exactly what you want to use here. – Jongware Dec 09 '13 at 21:10