Python 将scrapy转换为lxml

我有一段类似这样的代码

for row in response.css("div#flexBox_flex_calendar_mainCal table tr.calendar_row"):
    print "================" 
        print row.xpath(".//td[@class='time']/text()").extract()
        print row.xpath(".//td[@class='currency']/text()").extract()
        print row.xpath(".//td[@class='impact']/span/@title").extract()
        print row.xpath(".//td[@class='event']/span/text()").extract()
        print row.xpath(".//td[@class='actual']/text()").extract()
        print row.xpath(".//td[@class='forecast']/text()").extract()
        print row.xpath(".//td[@class='previous']/text()").extract()
    print "================" 

我可以用纯python得到同样的东西

from lxml import html
import requests

page = requests.get('http://www.forexfactory.com/calendar.php?day=dec1.2011')

tree = html.fromstring(page.text)

print tree.xpath(".//td[@class='time']/text()")
print tree.xpath(".//td[@class='currency']/text()")
print tree.xpath(".//td[@class='impact']/span/@title")
print tree.xpath(".//td[@class='event']/span/text()")
print tree.xpath(".//td[@class='actual']/text()")
print tree.xpath(".//td[@class='forecast']/text()")
print tree.xpath(".//td[@class='previous']/text()")

但是我需要一行一行地做。我第一次尝试移植到lxml失败：

from lxml import html
import requests

page = requests.get('http://www.forexfactory.com/calendar.php?day=dec1.2011')

tree = html.fromstring(page.text)

for row in tree.css("div#flexBox_flex_calendar_mainCal table tr.calendar_row"):
    print row.xpath(".//td[@class='time']/text()")
    print row.xpath(".//td[@class='currency']/text()")
    print row.xpath(".//td[@class='impact']/span/@title")
    print row.xpath(".//td[@class='event']/span/text()")
    print row.xpath(".//td[@class='actual']/text()")
    print row.xpath(".//td[@class='forecast']/text()")
    print row.xpath(".//td[@class='previous']/text()")

将此碎片代码移植到纯lxml的正确方法是什么？

编辑：我更接近了。我可以看到一个

表{}

对象，我只是不知道如何走它

import urllib2
from lxml import etree


#import requests

def wgetUrl(target):
    try:
        req = urllib2.Request(target)
        req.add_header('User-Agent', 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.0.3 Gecko/2008092417 Firefox/3.0.3')
        response = urllib2.urlopen(req)
        outtxt = response.read()
        response.close()
    except:
        return ''

    return outtxt


url = 'http://www.forexfactory.com/calendar.php?day='
date = 'dec1.2011'

data = wgetUrl(url + date)
parser = etree.HTMLParser()

tree   = etree.fromstring(data, parser)

for elem in tree.xpath("//div[@id='flexBox_flex_calendar_mainCal']"):
    print elem[0].tag, elem[0].attrib, elem[0].text
    # elem[1] is where the table is
    print elem[1].tag, elem[1].attrib, elem[1].text
    print elem[1]

---

我喜欢使用

lxml

进行刮削。我通常不使用它的

xpath

功能，而是选择它们的

ElementPath

库。它在语法上非常相似。下面是我如何移植你的

scrapy

代码

逐行：

初始化：

from lxml import etree

# analogous function xpath(.../text()).extract() for lxml etree nodes
def extract_text(elem):        
    if elem is None:
        print None
    else
        return ''.join(i for i in elem.itertext())

data = wgetUrl(url+date)  # wgetUrl, url, date you defined in your question
tree = etree.HTML(content)

第1行

# original
for row in response.css("div#flexBox_flex_calendar_mainCal table tr.calendar_row"):

# ported
for row in tree.findall(r'.//div[@id="flexBox_flex_calendar_mainCal"]//table/tr[@class="calendar_row"]'):

第2行

print "================" 

第3行

# original
print row.xpath(".//td[@class='time']/text()").extract()
# ported
print extract_text(row.find(r'.//td[@class="time"]'))

第4行

# original
print row.xpath(".//td[@class='currency']/text()").extract()
# ported
print extract_text(row.find(r'.//td[@class="currency"]'))

第5行

# original
print row.xpath(".//td[@class='impact']/span/@title").extract()
# ported
td = row.find(r'.//td[@class="impact"]/span')
if td is not None and 'title' in td.attrib:
    print td.attrib['title']

第6行

# original
print row.xpath(".//td[@class='event']/span/text()").extract()
# ported
print extract_text(row.find(r'.//td[@class="event"]/span'))

第7行

# original
print row.xpath(".//td[@class='actual']/text()").extract()
# ported
print extract_text(row.find(r'.//td[@class="actual"]'))

第8行

# original
print row.xpath(".//td[@class='forecast']/text()").extract()
# ported
print extract_text(row.find(r'.//td[@class="forecast"]'))

第9行

# original
print row.xpath(".//td[@class='previous']/text()").extract()
# ported
print extract_text(row.find(r'.//td[@class="previous"]'))

第10行

print "================" 

现在大家一起：

from lxml import etree

def wgetUrl(target):
    # same as you defined it

# analogous function xpath(.../text()).extract() for lxml etree nodes
def extract_text(elem):        
    if elem is None:
        print None
    else
        return ''.join(i for i in elem.itertext())

content = wgetUrl(your_url)  # wgetUrl as the function you defined in your question
node = etree.HTML(content)


for row in node.findall(r'.//div[@id="flexBox_flex_calendar_mainCal"]//table/tr[@class="calendar_row"]'):
    print "================" 
    print extract_text(row.find(r'.//td[@class="time"]'))
    print extract_text(row.find(r'.//td[@class="currency"]'))
    td = row.find(r'.//td[@class="impact"]/span')
    if td is not None and 'title' in td.attrib:
        print td.attrib['title']
    print extract_text(row.find(r'.//td[@class="event"]/span'))
    print extract_text(row.find(r'.//td[@class="actual"]'))
    print extract_text(row.find(r'.//td[@class="forecast"]'))
    print extract_text(row.find(r'.//td[@class="previous"]'))
    print "================"

---

谢谢农夫乔。我想我对如何从您的示例中使用scrapylxml有一个很好的想法。有没有一种方法可以说node.findall（r'.//div[@id=“flexBox\u flex\u calendar\u mainCal”]//table/tr[@class=“calendar*”]），这样它就可以匹配任何以“calendar”开头的行了？Ivan我想不出一个本机解决方案，但您可以只使用：

nodes=node.findall（r'.//div[@id=“flexBox\u flex\u calendar\u mainCal”]//table/tr[@class]'）

。这将为您提供具有

class

属性的所有

tr

节点，然后您可以自己对其进行筛选：

calendar\u节点=[node for node in nodes if node.attrib['class'].startswith（'calendar'）]

这一建议会导致正确的解决方案。谢谢农夫乔。