修改 XML 文件 - 除法值

Question

我希望通过除以 xml 文件来修改某些值。

我需要将 se:SvgParameter[name="stroke-width"] 和 se:Size 的值除以 3.6。我在 Python.org、Modifying an XML File 上找到了这个教程，但它似乎不起作用，我在这里找不到类似的东西。任何帮助或观点将不胜感激！

这是一些示例 XML，但我希望能够将脚本输出到包含多个文件的文件夹中并让它转换所有文件。

XML:

<?xml version="1.0" encoding="ISO-8859-1"?>
<StyledLayerDescriptor version="1.1.0" xmlns="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/StyledLayerDescriptor.xsd" xmlns:se="http://www.opengis.net/se">
  <NamedLayer>
    <se:Name>QGIS_SLD_ScaleProblem</se:Name>
    <se:Description>
      <se:Title>QGIS_SLD_ScaleProblem</se:Title>
      <se:Abstract>This SLD is in Pixels, but QGIS will read it as mm</se:Abstract>
    </se:Description>
    <UserStyle>
      <se:Name>QGIS_SLD_ScaleProblem</se:Name>
      <se:FeatureTypeStyle>
        <se:Rule>
          <se:Name>QGIS_SLD_ScaleProblem_Line</se:Name>
          <se:LineSymbolizer>
            <se:Name>Line</se:Name>
            <se:Stroke>
              <se:SvgParameter name="stroke">#FF0000</se:SvgParameter>
              <se:SvgParameter name="stroke-width">36</se:SvgParameter>
            </se:Stroke>
          </se:LineSymbolizer>
        </se:Rule>
        <se:Rule>
          <se:Name>QGIS_SLD_ScaleProblem_Point</se:Name>
          <se:PointSymbolizer>
            <se:Name>Point</se:Name>
            <se:Graphic>
             <se:Mark>
              <se:WellKnownName>circle</se:WellKnownName>
              <se:Fill>
               <se:SvgParameter name="fill">#FF0000</se:SvgParameter>
              </se:Fill>
             </se:Mark>
             <se:Size>36</se:Size>
            </se:Graphic>
          </se:PointSymbolizer>
        </se:Rule>
      </se:FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

代码：

import xml.etree.ElementTree as ET
from lxml import etree

tree = ET.parse('QGIS-SLD-ScaleProblem_Line.sld')
root = tree.getroot()

# To check that the script is reading the correct file
print("SLD file", root[0][0].text, "loaded.")

# Registers namespaces to prevent them being filled with defaults
ET.register_namespace('', "http://www.opengis.net/sld")
ET.register_namespace('ogc', "http://www.opengis.net/ogc")
ET.register_namespace('xsi', "http://www.w3.org/2001/XMLSchema-instance")
ET.register_namespace('xlink', "http://www.w3.org/1999/xlink")
ET.register_namespace('schemaLocation', "http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/StyledLayerDescriptor.xsd")
ET.register_namespace('se', "http://www.opengis.net/se")

# This section "should" search the XML for se:SvgParameter name="stroke-width" and se:Size and divide the value by 3.6
for SvgParameter in root.iter('SvgParameter'):
    new_SvgParameter = int(SvgParameter.text) / 3.6
    SvgParameter.text = str(new_SvgParameter)
for Size in root.iter('Size'):
    new_Size= int(Size.text) / 3.6
    Size.text = str(new_Size)

tree.write("GIS-SLD-ScaleFixed.sld", xml_declaration=True, encoding='ISO-8859-1')

我看过的答案：

How to update/modify a XML file in python?
Editing values in a xml file with Python
Python: Modifying an XML File
Modifying an XML File in python
Python modify an xml file

Answer 1

考虑 XSLT 设计用于转换 XML 文件的专用语言。 Python 的 lxml 模块可以运行 XSLT 1.0 脚本。此外，XSLT 可以运行在 Python 之外，因此具有可移植性。

只需调用 identity transform 即可按原样复制整个文档，然后运行在选定节点上进行划分。这种方法不需要 for 循环或 if 逻辑。

XSLT （另存为 .xsl 文件，格式良好的特殊 XML 文件）

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                              xmlns:se="http://www.opengis.net/se">                               
  <xsl:output indent="yes"/>
  <xsl:strip-space elements="*"/>

  <xsl:template match="@*|node()">
    <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="se:SvgParameter[@name='stroke-width']|se:Size">
    <xsl:copy>
        <xsl:apply-templates select="@*"/>
        <xsl:value-of select="format-number(text(), '#') div 3.6"/>
    </xsl:copy>
  </xsl:template>

</xsl:stylesheet>

Python （在多个文件的循环中迭代下面的过程）

import lxml.etree as et

# LOAD XML AND XSL
doc = et.parse('Input.xml')
xsl = et.parse('XSLTScript.xsl')

# TRANSFORM
transform = et.XSLT(xsl)
result = transform(doc)

# OUTPUT TO SCREEN    
print(result)

# OUTPUT TO FILE
with open('Output.xml', 'wb') as f:
    f.write(result)

输出

<?xml version="1.0"?>
<StyledLayerDescriptor xmlns="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:se="http://www.opengis.net/se" version="1.1.0" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/StyledLayerDescriptor.xsd">
  <NamedLayer>
    <se:Name>QGIS_SLD_ScaleProblem</se:Name>
    <se:Description>
      <se:Title>QGIS_SLD_ScaleProblem</se:Title>
      <se:Abstract>This SLD is in Pixels, but QGIS will read it as mm</se:Abstract>
    </se:Description>
    <UserStyle>
      <se:Name>QGIS_SLD_ScaleProblem</se:Name>
      <se:FeatureTypeStyle>
        <se:Rule>
          <se:Name>QGIS_SLD_ScaleProblem_Line</se:Name>
          <se:LineSymbolizer>
            <se:Name>Line</se:Name>
            <se:Stroke>
              <se:SvgParameter name="stroke">#FF0000</se:SvgParameter>
              <se:SvgParameter name="stroke-width">10</se:SvgParameter>
            </se:Stroke>
          </se:LineSymbolizer>
        </se:Rule>
        <se:Rule>
          <se:Name>QGIS_SLD_ScaleProblem_Point</se:Name>
          <se:PointSymbolizer>
            <se:Name>Point</se:Name>
            <se:Graphic>
              <se:Mark>
                <se:WellKnownName>circle</se:WellKnownName>
                <se:Fill>
                  <se:SvgParameter name="fill">#FF0000</se:SvgParameter>
                </se:Fill>
              </se:Mark>
              <se:Size>10</se:Size>
            </se:Graphic>
          </se:PointSymbolizer>
        </se:Rule>
      </se:FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

修改 XML 文件 - 除法值

Modifying an XML File - Dividing values

python

xml

lxml

sld