Xpath不返回值lxml Python

Question

我正在做一个项目，我试图让lxml从不同网页上的不同表格中提取股票数据。当我运行程序试图打印我试图提取的值时，我得到了空括号

('Cash_and_short_term_investments:', [])
('EPSNextYear:', [])

以下是我称之为的方式：

  #the url at this point is http://finviz.com/quote.ashx?t=RAIL confirmed with print statement
   url = driver.current_url
   page2 = requests.get(url)
   tree2 = html.fromstring(page2.content)
   EPSNextYear =              
   tree2.xpath('/html/body/table[3]/tr[1]/td/table/tr[7]/td/table/tr[2]/td[6]/b')
   #Original XPath:/html/body/table[3]/tbody/tr[1]/td/table/tbody/tr[7]/td/table/tbody/tr[2]/td[6]/b
   print ('EPSNextYear:', EPSNextYear)

以及：

#the url at this point is https://www.google.com/finance?q=NASDAQ%3ARAIL&fstype=ii&ei=hGwhWNHVPOW7iwLMiIfIDA I've confirmed this with a print
url = driver.current_url
page3 = requests.get(url)
tree3 = html.fromstring(page3.content)
Cash_and_Short_Term_Investments = tree3.xpath('//*[@id="fs-table"]/tr[3]/td[2]/text()')
print('Cash_and_short_term_investments:', Cash_and_Short_Term_Investments)

我已经从XPath中删除了tbody，就像一些类似的问题所建议的那样。任何帮助或建议将不胜感激，谢谢！

Answer 1

当提出这样的问题时，您需要提供一个简短但完整的示例来说明问题。

看看第二个示例，很明显，您使用的XPath表达式是不正确的。XPath中缺少tbody元素。（您可能希望通过查找正在搜索的实际字符串来选择正确的表行。）

给定以下代码：

from lxml import etree
import urllib

url="http://www.google.com/finance?q=NASDAQ%3ARAIL&fstype=ii&ei=hGwhWNHVPOW7iwLMiIfIDA"
parser = etree.HTMLParser()
tree = etree.parse(urllib.urlopen(url), parser)
result = tree.xpath('//*[@id="fs-table"]/tbody/tr[normalize-space(td) = "Cash and Short Term Investments"]')
for x in result: print etree.tostring(x)

这样运行时：

> python test.py 

您将获得以下输出：

<tr>
<td class="lft lm">Cash and Short Term Investments
</td>
<td class="r">39.78</td>
<td class="r">78.45</td>
<td class="r">91.21</td>
<td class="r">110.02</td>
<td class="r rm">125.01</td>
</tr>

<tr>
<td class="lft lm">Cash and Short Term Investments
</td>
<td class="r">110.02</td>
<td class="r">161.49</td>
<td class="r">184.49</td>
<td class="r rm">140.49</td>
</tr>

我相信，一旦你把第一个例子变成一个独立的问题复制器，你就能找出它的错误所在。