在Matlab中查找和替换XML文件行

Question

I have here an XML File, where I have to find the line numbers of a certain tag and then delete everything before that line.

I tried using xml2struct, but that doesn't give me the possibility to go to a certain linenumber and delete everything before that and then write it back into a new XML file.

Really sorry if this is not worded correctly, I am super new to Matlab and XML file structures...

This is the XML File: `

<?xml version="1.0" encoding="utf-8"?>
<SetBeam>
  <ControlPoints>
    <Cp>
      <Mu>1</Mu>
      <GantryRtn>40.79545455</GantryRtn>
      <Y1>4</Y1>
      <Y2>3.25</Y2>
      <X1>4.45455</X1>
      <X2>3.20455</X2>
      <Mlc>
        <ID>1</ID>
        <B>0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 -4.279 -4.279 1.812 2.395 0.687 3.187 3.219 2.363 3.469 3.469 2.594 1.043 0.25 1.5 3.75 3.75 3.75 3.75 3.75 1.062 -1.531 3.312 3.469 3.219 2.969 2.969 2.719 1.863 1.5 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125</B>
        <A>-0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 4.331 4.331 -1.656 -1.094 0.188 -1.594 -2.062 0.438 -1.582 0.938 -0.301 1.938 1.355 -0.812 2.688 -0.312 -0.5 2.387 -1.906 2.969 2.719 -2.387 -2.5 -2.219 2.469 -0.426 0.355 -0.062 -0.031 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125</A>
      </Mlc>
    </Cp>
    <Cp>
      <Mu>2</Mu>
      <GantryRtn>42.38636364</GantryRtn>
      <Y1>4</Y1>
      <Y2>3.25</Y2>
      <X1>4.45455</X1>
      <X2>3.20455</X2>
      <Mlc>
        <ID>1</ID>
        <B>0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 -4.279 -4.279 1.969 2.719 1.094 3.031 3.219 2.687 3.469 3.719 2.281 1.691 0.25 1.281 3.75 3.75 3.75 3.75 3.75 1.687 -1.156 3.312 3.281 3.219 2.969 2.969 2.719 1.5 1.5 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125 0.125</B>
        <A>-0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 4.331 4.331 -1.719 -1.062 0.188 -2.031 -1.719 0.313 -1.125 0.906 0.344 1.938 2.004 -0.75 2.688 -0.062 -0.094 2.688 -1.344 2.906 2.719 -2.125 -2.344 -1.625 2.469 -0.781 0.781 -0.062 -0.031 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125 -0.125</A>
      </Mlc>
    </Cp>
  </ControlPoints>
</SetBeam>

`

So basically I can navigate through the struct which I created with xml2struct and can extract the values of the nodes, but I couldn't find out, how I can navigate to, say, the node with text '2' and delete the whole node before the node which has the node with text '2'. Thanks for any help!

Answer 1

Lines aren't generally significant in XML, so thinking of this in terms of lines of the file (rather than the hierarchic XML structure) isn't really the right way to think of the problem, and is therefore going to give you problems because many XML parsers don't report line numbers.

Also, deleting everything before a particular line will almost certainly result in something that isn't well-formed XML.

If you want to delete all the <Cp> elements that precede the one with child <Mu>2</Mu> , you can do this in XSLT easily enough. You need one rule that copies everything through unchanged, which in XSLT 3.0 can be written

<xsl:mode on-no-match="shallow-copy"/>

but in earlier versions needs the more verbose

<xsl:template match="*">
  <xsl:copy><xsl:copy-of select="@*"/><xsl:apply-templates/></xsl:copy>
</xsl:template>

and then a second rule that deletes the selected elements:

<xsl:template match="Cp[following-sibling::Cp/Mu='2']"/>