XPath 排序不持久？答案

【问题标题】：XPath sorting not persistent?XPath 排序不持久？
【发布时间】：2023-03-14 00:51:02
【问题描述】：

我有以下 XML：

<doc>
<ActivityNarrativeInformation>
  <ActivityID>123456789</ActivityID>
  <ActivityNarrativeInformationID>111111111</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>1</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>She Sells Sea Shells by the Sea Shore and she also</ActivityNarrativeText>
  </ActivityNarrativeInformation>
 <ActivityNarrativeInformation>
  <ActivityID>123456789</ActivityID>
  <ActivityNarrativeInformationID>111111111</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>3</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>triple shot frappuccino, extra hot, with whipped cream in a tall cup </ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>123456789</ActivityID>
  <ActivityNarrativeInformationID>111111111</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>2</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>likes to take long walks on the beach while she drinks a</ActivityNarrativeText>
  </ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>987654321</ActivityID>
  <ActivityNarrativeInformationID>222222222</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>486</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>It was a dark and stormy night; the rain fell in torrents--except at occasional intervals, when
 </ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>987654321</ActivityID>
  <ActivityNarrativeInformationID>222222222</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>488</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>scene lies), rattling along the housetops, and fiercely agitating the scanty flame of the lamps that
</ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>987654321</ActivityID>
  <ActivityNarrativeInformationID>222222222</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>487</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>was checked by a violent gust of wind which swept up the streets (for it is in London that our
</ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>987654321</ActivityID>
  <ActivityNarrativeInformationID>222222222</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>489</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>struggled against the darkness.
</ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>55555555</ActivityID>
  <ActivityNarrativeInformationID>77777777</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>31921</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>Papa Bear was very big and growly. Mamma Bear was middle-sized and pleasant.
</ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>55555555</ActivityID>
  <ActivityNarrativeInformationID>77777777</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>31923</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>Papa bear loved to fix things around the house; Mama bear loved to grow flowers in her garden; and, Baby bear loved playing in the yard. They were very happy. </ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>55555555</ActivityID>
  <ActivityNarrativeInformationID>77777777</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>31920</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>Once upon a time there were three bears, Papa Bear, Mamma Bear and Baby Bear
</ActivityNarrativeText>
</ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>55555555</ActivityID>
  <ActivityNarrativeInformationID>77777777</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>31922</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>And Baby Bear, well, he was small, and
sometimes he squeaked! They lived in a pretty little house on the edge of the forest
</ActivityNarrativeText>
</ActivityNarrativeInformation>
</doc

我需要将 ActivityNarrativeInformation 元素按 ActivityID 分组并以这样的方式连接 ActivityNarrativeText，使其按 ActivityNarrativeSequenceNumber 排序

我设法使用以下 XPath 查询 (XPath 3.1) 对元素进行排序 sort(//ActivityNarrativeInformation[ActivityID=123456789], (), function($ActivityNarrativeSequenceNumber) {$ActivityNarrativeSequenceNumber})

所以结果是这样的：

<ActivityNarrativeInformation>
  <ActivityID>123456789</ActivityID>
  <ActivityNarrativeInformationID>111111111</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>1</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>She Sells Sea Shells by the Sea Shore and she also</ActivityNarrativeText>
  </ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>123456789</ActivityID>
  <ActivityNarrativeInformationID>111111111</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>2</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>likes to take long walks on the beach while she drinks a</ActivityNarrativeText>
  </ActivityNarrativeInformation>
<ActivityNarrativeInformation>
  <ActivityID>123456789</ActivityID>
  <ActivityNarrativeInformationID>111111111</ActivityNarrativeInformationID>
  <ActivityNarrativeSequenceNumber>3</ActivityNarrativeSequenceNumber>
  <ActivityNarrativeText>triple shot frappuccino, extra hot, with whipped cream in a tall cup </ActivityNarrativeText>
</ActivityNarrativeInformation>

然而问题是，如果我想通过在末尾添加/ActivityNarrativeText 来限制所有ActivityNarrativeText，就像这样

sort(//ActivityNarrativeInformation[ActivityID=123456789], (), function($ActivityNarrativeSequenceNumber) {$ActivityNarrativeSequenceNumber})/ActivityNarrativeText

或

sort(//ActivityNarrativeInformation[ActivityID=123456789]/ActivityNarrativeText, (), function($seq) {$seq/ActivityNarrativeSequenceNumber})

订单丢失：

<ActivityNarrativeText>She Sells Sea Shells by the Sea Shore and she also</ActivityNarrativeText>
<ActivityNarrativeText>triple shot frappuccino, extra hot, with whipped cream in a tall cup </ActivityNarrativeText>
<ActivityNarrativeText>likes to take long walks on the beach while she drinks a</ActivityNarrativeText>

我做错了什么？

【问题讨论】：

标签： xpath xpath-3.1

【解决方案1】：

当你写 /ActivityNarrativeText 时你会丢失顺序，它会以与输入文件中相同的顺序返回 <ActivityNarrativeText>

/something 带有节点不仅仅意味着将其映射到子节点。

意思是

映射它
将所有节点重新排序为输入文档顺序
删除重复项

你可以使用!ActivityNarrativeText

【讨论】：

【解决方案2】：

除了在排序后不使用/ 而是使用! 的正确答案之外，如果您的排序函数参数选择正确的元素作为排序键，您的尝试之一实际上会起作用：

sort(//ActivityNarrativeInformation[ActivityID=123456789]/ActivityNarrativeText, (), function($text) {$text/../ActivityNarrativeSequenceNumber})

【讨论】：

【解决方案3】：

如果您想做的是从特定的 ActivityID 的示例 xml 中提取一个 coherenet 句子，则此表达式

string-join(sort(//ActivityNarrativeInformation[ActivityID=123456789]/ActivityNarrativeText/concat(normalize-space()," "), (), function($ActivityNarrativeSequenceNumber) {$ActivityNarrativeSequenceNumber}))

应该输出

She Sells Sea Shells by the Sea Shore and she also likes to take long walks on the beach while she drinks a triple shot frappuccino, extra hot, with whipped cream in a tall cup

【讨论】：

在这里测试：videlibri.de/cgi-bin/xidelcgi，但结果仍然如描述的那样，即顺序不正确
@Macin 有趣；我在 Base-X 中尝试过，它可以工作，但现在它似乎只适用于特定的 ActivityID，但不适用于其他两个......让我进一步检查。

【解决方案4】：

在这里进行测试：videlibri.de/cgi-bin/xidelcgi

如果您使用的是xidel，请添加其标签。也许cmd 用于Windows，或者bash 用于Unix。

~~我不太确定这是否可以使用 XPath。~~ 我相信您最好使用 XQuery。

对于<ActivityID>123456789</ActivityID> 的叙述，您可以这样做：

$ xidel -s input.xml --xquery '
  normalize-space(
    for $x in //ActivityNarrativeInformation
    where $x/ActivityID = 123456789
    order by $x/ActivityNarrativeSequenceNumber
    return
    $x/ActivityNarrativeText
  )
'

我建议的所有叙述：

$ xidel -s input.xml --xquery '
  for $narrative at $i in //ActivityNarrativeInformation
  group by $id:=$narrative/ActivityID
  count $i
  return (
    $i,
    normalize-space(
      for $seq in $narrative
      order by $seq/ActivityNarrativeSequenceNumber
      return
      $seq/ActivityNarrativeText
    )
  )
'
1
Once upon a time there were three bears, [...]
2
She Sells Sea Shells by the Sea Shore and [...]
3
It was a dark and stormy night; the rain [...]

首先按<ActivityID> 分组，然后在另一个for 循环中按<ActivityNarrativeSequenceNumber> 对句子进行排序。

2021-07-05 更新；我忘记了 XPath 的!。在这种情况下，一个 for 循环就足够了：

$ xidel -s input.xml --xquery '
  for $narrative at $i in //ActivityNarrativeInformation
  order by $narrative/ActivityNarrativeSequenceNumber
  group by $id:=$narrative/ActivityID
  count $i
  return (
    $i,
    normalize-space($narrative ! ActivityNarrativeText)
  )
'

【讨论】：

normalize-space() 如何在这里处理序列？ normalize-space() 应该最多接受一个字符串。当将一系列字符串传递给 xidel 的 normalize-space() 时，它似乎只作用于第一个字符串。 Saxon 和 Zorba 都正确地给出了基数错误。在这个例子中，$narrative 是否总是只有一个项目？
@DavidDenenberg 不，$narrative 是一个序列。如果normalize-space() 和你的xidel 二进制文件只返回第一个字符串，那么你的二进制文件太旧了。 normalize-space() 接受序列作为输入。这至少是我对w3.org/TR/xpath-functions-31/#func-normalize-space 的解释。最近的 xidel 构建支持它。
是的，它似乎是一个较旧的二进制文件。我不会怀疑最新版本的 xidel 是否支持这一点，但这是对规范的错误解释。清楚地显示“xs:string?”作为参数（零个或一个原子字符串）。
@DavidDenenberg: Xidel 在standard XQuery mode 中也给出了一个错误。但是默认情况下所有类型检查都是禁用的，因为这样查询评估的运行速度会快 20%