Python: Split unicode string on word boundaries

Question

I need to take a string, and shorten it to 140 characters.

Currently I am doing:

if len(tweet) > 140:
    tweet = re.sub(r\"\\s+\", \" \", tweet)          


        

Answer 1

the re.U flag will treat \s according to the Unicode character properties database.

The given string, however, doesn't apparently contain any white space characters according to python's unicode database:

>>> x = u'\u7b80\u8baf\uff1a\u65b0\u83ef\u793e\u5831\u9053\uff0c\u7f8e\u570b\u7e3d\u7d71\u5967\u5df4\u99ac\u4e58\u5750\u7684\u300c\u7a7a\u8ecd\u4e00\u865f\u300d\u5c08\u6a5f\u665a\u4e0a10\u664242\u5206\u9032\u5165\u4e0a\u6d77\u7a7a\u57df\uff0c\u9810\u8a08\u7d0430\u5206\u9418\u5f8c\u62b5\u9054\u6d66\u6771\u570b\u969b\u6a5f\u5834\uff0c\u958b\u5c55\u4ed6\u4e0a\u4efb\u5f8c\u9996\u6b21\u8a2a\u83ef\u4e4b\u65c5\u3002'
>>> re.compile(r'\s+', re.U).split(x)
[u'\u7b80\u8baf\uff1a\u65b0\u83ef\u793e\u5831\u9053\uff0c\u7f8e\u570b\u7e3d\u7d71\u5967\u5df4\u99ac\u4e58\u5750\u7684\u300c\u7a7a\u8ecd\u4e00\u865f\u300d\u5c08\u6a5f\u665a\u4e0a10\u664242\u5206\u9032\u5165\u4e0a\u6d77\u7a7a\u57df\uff0c\u9810\u8a08\u7d0430\u5206\u9418\u5f8c\u62b5\u9054\u6d66\u6771\u570b\u969b\u6a5f\u5834\uff0c\u958b\u5c55\u4ed6\u4e0a\u4efb\u5f8c\u9996\u6b21\u8a2a\u83ef\u4e4b\u65c5\u3002']

Answer 2

After speaking with some native Cantonese, Mandarin, and Japanese speakers it seems that the correct thing to do is hard, but my current algorithm still makes sense to them in the context of internet posts.

Meaning, they are used to the "split on space and add … at the end" treatment.

So I'm going to be lazy and stick with it, until I get complaints from people that don't understand it.

The only change to my original implementation would be to not force a space on the last word since it is unneeded in any language (and use the unicode character … &#x2026 instead of ... three dots to save 2 characters)

Answer 3

What you're looking for is Chinese word segmentation tools. Word segmentation is not an easy task and is currently not perfectly solved. There are several tools:

1. CkipTagger

   Developed by Academia Sinica, Taiwan.

2. jieba

   Developed by Sun Junyi, a Baidu engineer.

3. pkuseg

   Developed by Language Computing and Machine Learning Group, Peking University

If what you want is character segmentation, it can be done albeit not very useful.

>>> s = u"简讯：新華社報道，美國總統奧巴馬乘坐的「空軍一號」專機晚上10時42分進入上海空域，預計約30分鐘後抵達浦東國際機場，開展他上任後首次訪華之旅。"
>>> chars = list(s)
>>> chars
[u'\u7b80', u'\u8baf', u'\uff1a', u'\u65b0', u'\u83ef', u'\u793e', u'\u5831', u'\u9053', u'\uff0c', u'\u7f8e', u'\u570b', u'\u7e3d', u'\u7d71', u'\u5967', u'\u5df4', u'\u99ac', u'\u4e58', u'\u5750', u'\u7684', u'\u300c', u'\u7a7a', u'\u8ecd', u'\u4e00', u'\u865f', u'\u300d', u'\u5c08', u'\u6a5f', u'\u665a', u'\u4e0a', u'1', u'0', u'\u6642', u'4', u'2', u'\u5206', u'\u9032', u'\u5165', u'\u4e0a', u'\u6d77', u'\u7a7a', u'\u57df', u'\uff0c', u'\u9810', u'\u8a08', u'\u7d04', u'3', u'0', u'\u5206', u'\u9418', u'\u5f8c', u'\u62b5', u'\u9054', u'\u6d66', u'\u6771', u'\u570b', u'\u969b', u'\u6a5f', u'\u5834', u'\uff0c', u'\u958b', u'\u5c55', u'\u4ed6', u'\u4e0a', u'\u4efb', u'\u5f8c', u'\u9996', u'\u6b21', u'\u8a2a', u'\u83ef', u'\u4e4b', u'\u65c5', u'\u3002']
>>> print('/'.join(chars))
简/讯/：/新/華/社/報/道/，/美/國/總/統/奧/巴/馬/乘/坐/的/「/空/軍/一/號/」/專/機/晚/上/1/0/時/4/2/分/進/入/上/海/空/域/，/預/計/約/3/0/分/鐘/後/抵/達/浦/東/國/際/機/場/，/開/展/他/上/任/後/首/次/訪/華/之/旅/。

Answer 4

For word segmentation in Chinese, and other advanced tasks in processing natural language, consider NLTK as a good starting point if not a complete solution -- it's a rich Python-based toolkit, particularly good for learning about NL processing techniques (and not rarely good enough to offer you viable solution to some of these problems).

Answer 5

I tried out the solution with PyAPNS for push notifications and just wanted to share what worked for me. The issue I had is that truncating at 256 bytes in UTF-8 would result in the notification getting dropped. I had to make sure the notification was encoded as "unicode_escape" to get it to work. I'm assuming this is because the result is sent as JSON and not raw UTF-8. Anyways here is the function that worked for me:

def unicode_truncate(s, length, encoding='unicode_escape'):
    encoded = s.encode(encoding)[:length]
    return encoded.decode(encoding, 'ignore')

Answer 6

Chinese doesn't usually have whitespace between words, and the symbols can have different meanings depending on context. You will have to understand the text in order to split it at a word boundary. In other words, what you are trying to do is not easy in general.