使用python和xpath选择多个值

Question

我可以在python中使用xpath选择单个值，但是如何将几个单独的xpath连接起来以获得一个值呢？
以下是html源代码（r.content）的示例片段：

<div class="members">
    <h2>Members</h2>
    <div class="member">
        <span title="Last Online:&nbsp;2017-02-20 22:37:42" data-time="2017-02-20T22:37:42Z">
          <span class="profile-link">
            <a href="/account/view-profile/KonterBolet">
              <img class="achievement" src="36.png" alt="Completed 36" title="Completed 36">KonterA</a>
          </span>
          <span class="memberType">Leader</span>
        </span>
    </div>
    <div class="member">
        <span title="Last Online:&nbsp;2017-02-19 11:28:20" data-time="2017-02-19T11:28:20Z">
          <span class="profile-link hasTwitch twitchOffline" data-twitch-user="mardok_tv">
            <a href="/account/view-profile/mardok">
              <img class="achievement" src="35.png" alt="Completed 35" title="Completed 35">mardok</a>
            <a class="twitch" href="//www.twitch.tv/mardok_tv" target="_blank" title="Offline"></a>
          </span>
          <span class="memberType">Officer</span>
        </span>
    </div>
</div>

我使用pythonrequests来获取内容，lxml来解析它

^{pr2}$

第一个xpath:
acc = webContent.xpath("//span/a[contains(@href,'account/view-profile')]/text()")
结果：
['konterA', 'mardok']

第二个xpath:
twitch = webContent.xpath('//span/@data-twith-user')
结果：
['mardok_tv']

第三个xpath:
lastOnline = webContent.xpath('//span/@data-time')
结果：
['2017-02-20T22:37:42Z','2017-02-19T11:28:20Z']

如何将这三者结合起来得到这样的结果：
[['konterA','','2017-02-20T22:37:42Z'],['mardok','mardok_tv','2017-02-19T11:28:20Z']

Answer 1

考虑分析同一父级下的所有项，在顶层xpath上迭代。如果不存在attrib/element值，则使用XPath的concat()返回一个空长度的字符串''。下面还使用XPath的normalize-space()从值中删除换行符和回车符。在

# PARSING POSTED SNIPPET AS STRING
webContent = html.fromstring(htmlstr)

# INITIALIZING LISTS
acc = []; twitch = []; lastOnline = []

# ITERATING THROUGH SECOND CHILD <SPAN>
for i in webContent.xpath("//span/span[1]"):    
    acc.append(i.xpath("concat(normalize-space(a[contains(@href,'account/view-profile')]),'')"))
    twitch.append(i.xpath("concat(@data-twitch-user, '')"))
    lastOnline.append(i.xpath("concat(../@data-time, '')"))

# ZIP EQUAL LENGTH LISTS
xpath_list = list(zip(acc, twitch, lastOnline))

print(xpath_list)
# [('KonterA', '', '2017-02-20T22:37:42Z'), ('mardok', 'mardok_tv', '2017-02-19T11:28:20Z')]

Answer 2

我们叫它们first_list, second_list and third_list。 将second_list修改为：

second_list = [ i if i.strip("_tv") in first_list else "" for i in second_list ]

之后，请执行以下操作：

^{pr2}$

这应该以同样的方式给您一个元组列表。在

[('konterA','','2017-02-20T22:37:42Z'),('mardok','mardok_tv','2017-02-19T11:28:20Z')]