试图了解XSLT Muenchian方法转换

Question

在寻找一种将XML文件中的元素进行分组的方法时，我遇到了Muenchian Method。

来源

<file>
    <patient>
        <Lab_Specimen_Number>L,18.1342718.Y</Lab_Specimen_Number>
        <Patient_Number>LOC0000015</Patient_Number>
        <ORG/>
        <Specimen/>
        <Antibiotic_Amox_Ampicillin/>
    </patient>
    <patient>
        <Lab_Specimen_Number>L,18.1342727.V</Lab_Specimen_Number>
        <Patient_Number>LOC0000001</Patient_Number>
        <ORG>Coliform</ORG>
        <Specimen>L,18.1342727.VA</Specimen>
        <Antibiotic_Amox_Ampicillin>S</Antibiotic_Amox_Ampicillin>
    </patient>
    <patient>
        <Lab_Specimen_Number/>
        <Patient_Number/>
        <ORG>Staphylococcus aureus</ORG>
        <Specimen>L,18.1342727.VA</Specimen>
        <Antibiotic_Amox_Ampicillin>S</Antibiotic_Amox_Ampicillin>
    </patient>
    <patient>
        <Lab_Specimen_Number>L,18.1346290.T</Lab_Specimen_Number>
        <Patient_Number>LOC0000001</Patient_Number>
        <ORG>Coliform</ORG>
        <Specimen>L,18.1346290.TA</Specimen>
        <Antibiotic_Amox_Ampicillin>S</Antibiotic_Amox_Ampicillin>
    </patient>
    <patient>
        <Lab_Specimen_Number>L,18.1342713.X</Lab_Specimen_Number>
        <Patient_Number>LOC0000009</Patient_Number>
        <ORG/>
        <Specimen/>
        <Antibiotic_Amox_Ampicillin/>
    </patient>
</file>

根据文章，我将键分配给patient[Specimen != '']而不是patient时更改了匹配项，因为“标本”值可能为空，并且最终输出中会丢失这些值如果仅使用patient。

转化

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
  <xsl:strip-space elements="*"/>
  <xsl:key name="patients-by-specimen" match="patient[Specimen != '']" use="Specimen" />
  <xsl:template match="file">
    <file>
      <xsl:for-each select="patient[count(. | key('patients-by-specimen', Specimen)[1]) = 1]">
        <patient>
          <xsl:copy-of select="Lab_Specimen_Number" />
          <xsl:copy-of select="Patient_Number" />
          <Specimen>
            <xsl:copy-of select="Specimen" />
            <Organisms>
              <xsl:for-each select="key('patients-by-specimen', Specimen)">
                <Organism>
                  <xsl:copy-of select="ORG"/>
                  <xsl:copy-of select="Antibiotic_Amox_Ampicillin"/>
                </Organism>
              </xsl:for-each>
            </Organisms>
          </Specimen>
        </patient>
      </xsl:for-each>
    </file>
  </xsl:template>
</xsl:stylesheet>

尽管上面的转换为我提供了所需的输出，但我不完全了解此行的工作方式：

<xsl:for-each select="patient[count(. | key('patients-by-specimen', Specimen)[1]) = 1]">

有人可以在我的源文件的上下文中解释此迭代吗？

输出

<file>
  <patient>
    <Lab_Specimen_Number>L,18.1342718.Y</Lab_Specimen_Number>
    <Patient_Number>LOC0000015</Patient_Number>
    <Specimen>
      <Specimen/>
      <Organisms/>
    </Specimen>
  </patient>
  <patient>
    <Lab_Specimen_Number>L,18.1342727.V</Lab_Specimen_Number>
    <Patient_Number>LOC0000001</Patient_Number>
    <Specimen>
      <Specimen>L,18.1342727.VA</Specimen>
      <Organisms>
        <Organism>
          <ORG>Coliform</ORG>
          <Antibiotic_Amox_Ampicillin>S</Antibiotic_Amox_Ampicillin>
        </Organism>
        <Organism>
          <ORG>Staphylococcus aureus</ORG>
          <Antibiotic_Amox_Ampicillin>S</Antibiotic_Amox_Ampicillin>
        </Organism>
      </Organisms>
    </Specimen>
  </patient>
  <patient>
    <Lab_Specimen_Number>L,18.1346290.T</Lab_Specimen_Number>
    <Patient_Number>LOC0000001</Patient_Number>
    <Specimen>
      <Specimen>L,18.1346290.TA</Specimen>
      <Organisms>
        <Organism>
          <ORG>Coliform</ORG>
          <Antibiotic_Amox_Ampicillin>S</Antibiotic_Amox_Ampicillin>
        </Organism>
      </Organisms>
    </Specimen>
  </patient>
  <patient>
    <Lab_Specimen_Number>L,18.1342713.X</Lab_Specimen_Number>
    <Patient_Number>LOC0000009</Patient_Number>
    <Specimen>
      <Specimen/>
      <Organisms/>
    </Specimen>
  </patient>
</file>