98 lines
4.0 KiB
Python
98 lines
4.0 KiB
Python
from scrapy.http import Request
|
|
from scrapy import log
|
|
from source import Source
|
|
from scrapy.selector import Selector
|
|
from FourmiCrawler.items import Result
|
|
import re
|
|
|
|
|
|
class WikipediaParser(Source):
|
|
|
|
""" Wikipedia scraper for chemical properties
|
|
|
|
This parser parses Wikipedia infoboxes (also bordered) to obtain properties and their values.
|
|
It also returns requests with other external sources which contain information on parsed subject.
|
|
"""
|
|
|
|
website = "http://en.wikipedia.org/wiki/*"
|
|
__spider = None
|
|
searched_compounds = []
|
|
|
|
def __init__(self):
|
|
Source.__init__(self)
|
|
|
|
def parse(self, response):
|
|
""" Distributes the above described behaviour """
|
|
log.msg('A response from %s just arrived!' % response.url, level=log.DEBUG)
|
|
sel = Selector(response)
|
|
compound = sel.xpath('//h1[@id="firstHeading"]//span/text()').extract()[0] # makes sure to use main page
|
|
if compound in self.searched_compounds:
|
|
return None
|
|
else:
|
|
items = self.parse_infobox(sel)
|
|
self.searched_compounds.append(compound)
|
|
return items
|
|
|
|
def parse_infobox(self, sel):
|
|
""" scrape data from infobox on wikipedia. """
|
|
items = []
|
|
|
|
#be sure to get both chembox (wikipedia template) and drugbox (wikipedia template) to scrape
|
|
tr_list = sel.xpath('.//table[@class="infobox bordered" or @class="infobox"]//td[not(@colspan)]').\
|
|
xpath('normalize-space(string())')
|
|
prop_names = tr_list[::2]
|
|
prop_values = tr_list[1::2]
|
|
for i, prop_name in enumerate(prop_names):
|
|
item = Result({
|
|
'attribute': prop_name.extract().encode('utf-8'),
|
|
'value': prop_values[i].extract().encode('utf-8'),
|
|
'source': "Wikipedia",
|
|
'reliability': "",
|
|
'conditions': ""
|
|
})
|
|
items.append(item)
|
|
log.msg('Wiki prop: |%s| |%s| |%s|' % (item['attribute'], item['value'], item['source']), level=log.DEBUG)
|
|
items = filter(lambda a: a['value'] != '', items) # remove items with an empty value
|
|
itemlist = self.cleanitems(items)
|
|
|
|
identifiers = self.get_identifiers(sel)
|
|
|
|
#add extra sources to scrape from as requests
|
|
for i, identifier in enumerate(identifiers):
|
|
request = None
|
|
#discard internal wikipedia links
|
|
if re.match('//en\.wikipedia', identifier):
|
|
log.msg('Found link to wikipedia, this is not something to scrape: %s' % identifier, level=log.WARNING)
|
|
#fix links starting with '//www.'
|
|
elif re.match('/{2}', identifier):
|
|
identifier = re.sub("/{2}", "http://", identifier)
|
|
request = Request(identifier)
|
|
else:
|
|
request = Request(identifier)
|
|
log.msg('New identifier found, request: %s' % identifier, level=log.DEBUG)
|
|
itemlist.append(request)
|
|
|
|
return itemlist
|
|
|
|
def new_compound_request(self, compound):
|
|
return Request(url=self.website[:-1] + compound, callback=self.parse)
|
|
|
|
@staticmethod
|
|
def cleanitems(items):
|
|
""" clean up properties using regex, makes it possible to split the values from the units """
|
|
for item in items:
|
|
value = item['value']
|
|
m = re.search('F;\s(\d+[\.,]?\d*)', value) # clean up numerical Kelvin value (after F)
|
|
if m:
|
|
item['value'] = m.group(1) + " K"
|
|
m = re.match('(\d+[\.,]?\d*)\sJ\sK.+mol', value) # clean up J/K/mol values
|
|
if m:
|
|
item['value'] = m.group(1) + " J/K/mol"
|
|
return items
|
|
|
|
@staticmethod
|
|
def get_identifiers(sel):
|
|
""" find external links, named 'Identifiers' to different sources. """
|
|
links = sel.xpath('//span[contains(concat(" ",normalize-space(@class)," "),"reflink")]/a'
|
|
'[contains(concat(" ",normalize-space(@class)," "),"external")]/@href').extract()
|
|
return links |