从 table 中提取行

Question

我正在尝试从以下 table:

中提取具有相应单元格的行

<table border="0" cellspacing="1" cellpading="3" width="100%">
<tr bgcolor="#505050">
    <td><b></b></td>
    <td colspan="2" align="center" class="white"><b>Last Day</b></td>
    <td colspan="2" align="center" class="white"><b>Last Week</b></td>
</tr>
<tr bgcolor="#505050">
    <td class="white"><b>Race</b></td>
    <td align="center" class="white"><b>Killed Players</b></td>
    <td align="center" class="white"><b>Killed by Players</b></td>
    <td align="center" class="white"><b>Killed Players</b></td>
    <td align="center" class="white"><b>Killed by Players</b></td>
</tr>
<tr bgcolor="#F1E0C6">
    <td>A</td>
    <td align="right">0</td>
    <td align="right">3</td>
    <td align="right">0</td>
    <td align="right">13</td>
</tr>
<tr bgcolor="#D4C0A1">
    <td>B</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">7</td>
</tr>
<tr bgcolor="#F1E0C6">
    <td>C</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">1</td>
</tr>
<tr bgcolor="#D4C0A1">
    <td>D</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">7</td>
</tr>
<tr bgcolor="#505050">
    <td class=white><b>Total</b></td>
    <td align="right" class="white"><b>210</b></td>
    <td align="right" class="white"><b>1060458</b></td>
    <td align="right" class="white"><b>1132</b></td>
    <td align="right" class="white"><b>5585115</b></td>
</tr>

我感兴趣的行是 A、B、C 等旁边带有数字的行。

我想到的解决办法是：

table = tree.xpath("//table/tr[td[not(contains(@class, 'white'))]]")

for tr in table:
    print( tr.xpath('td/text()'))

但是，输出仍然包括带有空单元格的第一行和最后 Day/Week 行，看起来像这样：

['', 'Last Day', 'Last Week']
['A', '0', '3', '0', '13']
['B', '0', '0', '2', '0']
['C', '0', '3', '0', '5']

怎样才能摆脱它？

Answer 1

只要把tr改成：

tr[not(contains(@bgcolor, "505050"))]

所以你的代码应该是这样的：

from lxml import html

HTML = """<table border="0" cellspacing="1" cellpading="3" width="100%">
<tr bgcolor="#505050">
    <td><b></b></td>
    <td colspan="2" align="center" class="white"><b>Last Day</b></td>
    <td colspan="2" align="center" class="white"><b>Last Week</b></td>
</tr>
<tr bgcolor="#505050">
    <td class="white"><b>Race</b></td>
    <td align="center" class="white"><b>Killed Players</b></td>
    <td align="center" class="white"><b>Killed by Players</b></td>
    <td align="center" class="white"><b>Killed Players</b></td>
    <td align="center" class="white"><b>Killed by Players</b></td>
</tr>
<tr bgcolor="#F1E0C6">
    <td>A</td>
    <td align="right">0</td>
    <td align="right">3</td>
    <td align="right">0</td>
    <td align="right">13</td>
</tr>
<tr bgcolor="#D4C0A1">
    <td>B</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">7</td>
</tr>
<tr bgcolor="#F1E0C6">
    <td>C</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">1</td>
</tr>
<tr bgcolor="#D4C0A1">
    <td>D</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">0</td>
    <td align="right">7</td>
</tr>
<tr bgcolor="#505050">
    <td class=white><b>Total</b></td>
    <td align="right" class="white"><b>210</b></td>
    <td align="right" class="white"><b>1060458</b></td>
    <td align="right" class="white"><b>1132</b></td>
    <td align="right" class="white"><b>5585115</b></td>
</tr>"""

tree = html.fromstring(HTML)
results = defaultdict

for item in tree.xpath('//table/tr[not(contains(@bgcolor, "505050"))]'):
    print item.xpath('.//td/text()')

并且输出：

['A', '0', '3', '0', '13']
['B', '0', '0', '0', '7']
['C', '0', '0', '0', '1']
['D', '0', '0', '0', '7']

不过，我还是建议使用 dict()。参见：

tree = html.fromstring(HTML)
results = dict()

def unpack(data):
    return data[0], data[1:]

for item in tree.xpath('//table/tr[not(contains(@bgcolor, "505050"))]'):
    key, values = unpack(item.xpath('.//td/text()'))
    results[key] = values

print results

输出：

{
    'A': ['0', '3', '0', '13'],
    'C': ['0', '0', '0', '1'],
    'B': ['0', '0', '0', '7'],
    'D': ['0', '0', '0', '7']
}

In Python 3, there is not need to have a unpack() function like the above one, you would just need to change key, values = unpack(item.xpath('.//td/text()')) to key, *values = item.xpath('.//td/text()')

参见：https://www.python.org/dev/peps/pep-3132/

此外，如果需要，您可以使用 sorted():

按字母（键）对结果进行排序

[
  ('A', ['0', '3', '0', '13']),
  ('B', ['0', '0', '0', '7']),
  ('C', ['0', '0', '0', '1']),
  ('D', ['0', '0', '0', '7'])
]

从 table 中提取行

Extracting rows from a table

python

xpath

lxml