python - 如何使用 html 中的已知文本考虑前面的元素？

Question

我有这样的html:我需要使用当前时间列旁边的上升/下降列[第10列]来获取当前时间!

<table id="table" class="tablesorter">
    <thead>
        <tr>
            <th rowspan="2"><div align="center">Sno</div></th>
            <th rowspan="2"><div align="center">Site Id</div></th>
            <th rowspan="2"><div align="center">Mandal</div></th>
            <th rowspan="2"><div align="center">Piezometer
              Location
          (Village) </div></th>
                <th rowspan="2" ><div align="center">July-18
              15/05/2018 <br>10:00 HRS</div></th>

            <th rowspan="2" ><div align="center">Nov-18</div></th>
            <th rowspan="2" ><div align="center">May-19</div></th>
            <th rowspan="2" ><div align="center">June-19</div></th>
            <th rowspan="2" ><div align="center">July-19
              15/07/2019 <br>10:00 HRS</div></th>
            <th colspan="4" ><div align="center">Rise(+)/Fall(-) from current water level
          and with reference to</div></th>
        </tr>
        <tr>
          <th ><div align="center">July-18</div></th>
          <th ><div align="center">Nov-18</div></th>
          <th ><div align="cesnter">May-19</div></th>
                  <th ><div align="cesnter">Jun-19</div></th>
        </tr>
    </thead>
    <tbody>
      <div align="center">

我的目标是获取位于“上升/下降”列之前的当前时间。这是我写的代码

import requests
from lxml import html 
url = 'http://www.apsdps.gov.in/gw_status.jsp?s1=1'
def scrape():
    print("start round")
    try:
        r=requests.get(url)
        d=r.content.decode(r.encoding)
        tree=html.fromstring(d)
        table = tree.xpath("//table[@id='table']")[0]
        fq_time_ele = tree.xpath("//table[@id='table']//thead//th//[contains(text(),'Rise(+)/Fall(-) from current water level and with reference to')]//preceding-sibling::th[1]//text()")
        curdate = fq_time_ele[0].strip().split()[-1].replace("/", "-")
        curtime = fq_time_ele[1].split(" ")[0].split(":")[0]
        time_str = curdate + "_" + curtime
        print(time_str)
    except Exception as e:
        print("Error ", str(e)) 
    print("end round")
try:
    scrape()
except:
    print("It is not working")

我需要当前时间，但代码不起作用。谁能帮我吗？

Answer 1

使用以下方法和更正的 xpath:

import requests
from lxml import html

url = 'http://www.apsdps.gov.in/gw_status.jsp?s1=1'


def scrape():
    print("start round")
    try:
        content = requests.get(url).content
        tree = html.fromstring(content)
        curr_time_parts = tree.xpath("//table[@id='table']//th[*[contains(text(),'Rise(+)/Fall(-)')]]"
                                     "/preceding-sibling::th[1]/*/text()")
        date_, time_ = curr_time_parts
        date_ = ' '.join(date_.split())
        print(date_, time_)
    except Exception as e:
        print("Error ", str(e))
    print("end round")


try:
    scrape()
except:
    print("It is not working")

输出:

start round
July-19 16/07/2019 16:00 HRS
end round