非换空间在我的scrapy蜘蛛选择标签,我想只有<p>
与文本内容来选择:Scrapy:与使用XPath
item['Description'] = response.xpath('//*[@id="textepresentation"]//p[string(.)]').extract()
它工作正常,但不幸的是,这样做,我也得空<p>
与非打破空间
u'<p>\xa0</p>',
如何避免与XPath的非换空间中选择<p>
?
非换空间在我的scrapy蜘蛛选择标签,我想只有<p>
与文本内容来选择:Scrapy:与使用XPath
item['Description'] = response.xpath('//*[@id="textepresentation"]//p[string(.)]').extract()
它工作正常,但不幸的是,这样做,我也得空<p>
与非打破空间
u'<p>\xa0</p>',
如何避免与XPath的非换空间中选择<p>
?
可以使用XPath's normalize-space()
字符串函数此一对夫妇谓词:
[normalize-space()]
让你得到与非空字符串表示的元素,但不包括开头和结尾的空白[not(contains(normalize-space(), "\u00a0"))]
因为NO-BREAK SPACE
未被删除(请参见this other answer where I checked which ones work,您可能需要添加其他字符进行测试)样品:
>>> import scrapy
>>> selector = scrapy.Selector(text=u'''
... <html>
... <p> </p>
... <p>something</p>
... <p> </p>
... <p><a href="http://example.com">some link</a></p>
... </html>
... ''')
>>> selector.xpath(u'''
... //p[normalize-space()]
... [not(contains(normalize-space(), "\u00a0"))]
... ''').extract()
[u'<p>something</p>', u'<p><a href="http://example.com">some link</a></p>']
>>>
编辑:
以下的中@ Kimmy的回答,这里是1个谓词替代方案,其他空格字符和:
normalize-space()
translate()
呼叫与'这里有云:
>>> chars = '''
... #CHARACTER TABULATION
... #LINE FEED
... #LINE TABULATION
... #FORM FEED
... #CARRIAGE RETURN
... #SPACE
... #NEXT LINE
... NO-BREAK SPACE
... OGHAM SPACE MARK
... MONGOLIAN VOWEL SEPARATOR
... EN QUAD
... EM QUAD
... EN SPACE
... EM SPACE
... THREE-PER-EM SPACE
... FOUR-PER-EM SPACE
... SIX-PER-EM SPACE
... FIGURE SPACE
... PUNCTUATION SPACE
... THIN SPACE
... HAIR SPACE
... ZERO WIDTH SPACE
... ZERO WIDTH NON-JOINER
... ZERO WIDTH JOINER
... LINE SEPARATOR
... PARAGRAPH SEPARATOR
... NARROW NO-BREAK SPACE
... MEDIUM MATHEMATICAL SPACE
... WORD JOINER
... IDEOGRAPHIC SPACE
... ZERO WIDTH NO-BREAK SPACE
... '''
>>> import unicodedata
>>> wsp = [unicodedata.lookup(c)
... for c in chars.splitlines()
... if c.strip() and not c.startswith('#')]
>>>
>>> # somehow NEXT LINE (U+0085) does not work with unicodedata
... wsp.append(u'\u0085')
>>>
>>> selector.xpath(u'''
... //p[normalize-space(translate(., "%(in)s", "%(out)s"))]
... ''' % {'in': ''.join(wsp),
... 'out': ' '*len(wsp)
... }).extract()
[u'<p>something</p>', u'<p><a href="http://example.com">some link</a></p>']
>>>
//p[translate(string(.),"\xa0","")]
不错的尝试,但'项目[ '说明'] = response.xpath(” // * [@ id =“textepresentation”] // p [translate(string(。),'\ xa0','')]')。extract() SyntaxError:行结束符后续字符' – jacquesseite
@jacquesseite字符串分隔符冲突。在XPath表达式中始终使用双引号,即translate(string(。),“\ xa0”,“”)' – har07
编辑为使用双引号。 –
谢谢你这个有价值的详细解释!它按预期工作。谢谢 ! – jacquesseite