Lara M. Lara M. - 1 month ago 7
Python Question

Strip \n \t \r in scrapy

I'm trying to strip \r \n \t characters with a scrapy spider, making then a json file.

I have a "description" object which is full of new lines, and it doesn't do what I want: matching each description to a title.

I tried with map(unicode.strip()) but it doesn't really works. Being new to scrapy I don't know if there's another simpler way or how map unicode really works.

This is my code:

def parse(self, response):
for sel in response.xpath('//div[@class="d-grid-main"]'):
item = xItem()
item['TITLE'] = sel.xpath('xpath').extract()
item['DESCRIPTION'] = map(unicode.strip, sel.xpath('//p[@class="class-name"]/text()').extract())


I tried also with:

item['DESCRIPTION'] = str(sel.xpath('//p[@class="class-name"]/text()').extract()).strip()


But it raised an error. What's the best way?

Answer Source

unicode.strip only deals with whitespace characters at the beginning and end of strings

Return a copy of the string with the leading and trailing characters removed.

not with \n, \r, or \t in the middle.

You can either use a custom method to remove those characters inside the string (using the regular expression module), or even use XPath's normalize-space()

returns the argument string with whitespace normalized by stripping leading and trailing whitespace and replacing sequences of whitespace characters by a single space.

Example python shell session:

>>> text='''<html>
... <body>
... <div class="d-grid-main">
... <p class="class-name">
... 
...  This is some text,
...  with some newlines \r
...  and some \t tabs \t too;
... 
... <a href="http://example.com"> and a link too
...  </a>
... 
... I think we're done here
... 
... </p>
... </div>
... </body>
... </html>'''
>>> response = scrapy.Selector(text=text)
>>> response.xpath('//div[@class="d-grid-main"]')
[<Selector xpath='//div[@class="d-grid-main"]' data=u'<div class="d-grid-main">\n<p class="clas'>]
>>> div = response.xpath('//div[@class="d-grid-main"]')[0]
>>> 
>>> # you'll want to use relative XPath expressions, starting with "./"
>>> div.xpath('.//p[@class="class-name"]/text()').extract()
[u'\n\n This is some text,\n with some newlines \r\n and some \t tabs \t too;\n\n',
 u"\n\nI think we're done here\n\n"]
>>> 
>>> # only leading and trailing whitespace is removed by strip()
>>> map(unicode.strip, div.xpath('.//p[@class="class-name"]/text()').extract())
[u'This is some text,\n with some newlines \r\n and some \t tabs \t too;', u"I think we're done here"]
>>> 
>>> # normalize-space() will get you a single string on the whole element
>>> div.xpath('normalize-space(.//p[@class="class-name"])').extract()
[u"This is some text, with some newlines and some tabs too; and a link too I think we're done here"]
>>>