如何使用最大子属性来更新XML属性节点？

Question

考虑以下XML：

<?xml version="1.0"?>
<sportsClass>
    <pupils>
        <pupil name="Adam" highestJump="">
            <jump height="4"/>
            <jump height="1"/>
        </pupil>
        <pupil name="Berta" highestJump="">
            <jump height="4"/>
            <jump height="7"/>
        </pupil>
        <pupil name="Caesar" highestJump="">
            <jump height="1"/>
            <jump height="2"/>
        </pupil>
        <pupil name="Doris" highestJump="">
            <jump height="5"/>
            <jump height="5"/>
        </pupil>
    </pupils>
</sportsClass>

如何使用xmlstarlet用相应的最大highestJump值填充height属性节点？

Answer 1

此问题包括两个子问题：

查找最大值

xmlstarlet没有max()函数，因此我们必须找到解决方法：

cat jumps.xml | \
xmlstarlet select -t -v "//pupil/jump[not(@height <= following-sibling::jump/@height) and not(@height < preceding-sibling::jump/@height)]/@height"

注意<=和< –如果有多个最大值，则仅取最后一个。
结果：
4
7
2
5

更新属性
恒定的实践价值
cat jumps.xml | xmlstarlet edit --update //pupil/@highestJump -v "Hahahaha"

...将Hahahaha写入每个highestJump属性。
简单XPath
注意：用于替换的XPath

相对于所选属性（因此.是
• 属性本身）]
必须用例如。 string()生效

所以：

cat jumps.xml | xmlstarlet edit --update //pupil/@highestJump -x "string(../@name)"

...给（缩短）：
<pupil name="Adam" highestJump="Adam">
<pupil name="Berta" highestJump="Berta">
<pupil name="Caesar" highestJump="Caesar">
<pupil name="Doris" highestJump="Doris">

将两者结合
cat jumps.xml | xmlstarlet edit --update //pupil/@highestJump -x "string(../jump[not(@height <= following-sibling::jump/@height) and not(@height < preceding-sibling::jump/@height)]/@height)"

...给......>
<?xml version="1.0"?>
<sportsClass>
  <pupils>
    <pupil name="Adam" highestJump="4">
      <jump height="4"/>
      <jump height="1"/>
    </pupil>
    <pupil name="Berta" highestJump="7">
      <jump height="4"/>
      <jump height="7"/>
    </pupil>
    <pupil name="Caesar" highestJump="2">
      <jump height="1"/>
      <jump height="2"/>
    </pupil>
    <pupil name="Doris" highestJump="5">
      <jump height="5"/>
      <jump height="5"/>
    </pupil>
  </pupils>
</sportsClass>