从另一个写入 KML 文件

Question

我正在努力：

- read a KML file
- remove the Placemark element if name = 'ZONE'
- write a new KML file without the element

这是我的代码：

from pykml import parser
kml_file_path = '../Source/Lombardia.kml'

removeList = list()

with open(kml_file_path) as f:
 folder = parser.parse(f).getroot().Document.Folder

for pm in folder.Placemark:
    if pm.name == 'ZONE':
        removeList.append(pm)
        print pm.name

for tag in removeList:
    parent = tag.getparent()
    parent.remove(tag)
#Write the new file
#I cannot reach the solution help me

这是 KML：

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
<Document>
    <name>Lombardia</name>
    <Style>
    ...
    </Style>
    <Folder>
<Placemark>
            <name>ZOGNO</name>
            <styleUrl>#FEATURES_LABELS</styleUrl>
            <Point>
                <coordinates>9.680530595139061,45.7941656233647,0</coordinates>
            </Point>
        </Placemark>
        <Placemark>
            <name>ZONE</name>
            <styleUrl>#FEATURES_LABELS</styleUrl>
            <Point>
                <coordinates>10.1315885854064,45.7592449779275,0</coordinates>
            </Point>
        </Placemark>
    </Folder>
</Document>
</kml>

问题是，当我编写新的 KML 文件时，它仍然有我要删除的元素。事实上，我想删除包含 name = ZONE 的元素。我做错了什么？谢谢。

--- 最终代码 感谢@Dawid Ferenczy，这是工作代码：

from lxml import etree
import pykml
from pykml import parser

kml_file_path = '../Source/Lombardia.kml'

# parse the input file into an object tree
with open(kml_file_path) as f:
  tree = parser.parse(f)

# get a reference to the "Document.Folder" node
folder = tree.getroot().Document.Folder

# iterate through all "Document.Folder.Placemark" nodes and find and remove all nodes
# which contain child node "name" with content "ZONE"
for pm in folder.Placemark:
    if pm.name == 'ZOGNO':
        parent = pm.getparent()
        parent.remove(pm)

# convert the object tree into a string and write it into an output file
with open('output.kml', 'w') as output:
    output.write(etree.tostring(folder, pretty_print=True))

Answer 1

您的代码中存在以下问题：

您没有将整个解析的对象树存储在任何地方（您只有对节点“Document.Folder”的引用：folder = parser.parse(f).getroot().Document.Folder）但是你想把它写回一个文件，所以你需要存储它
我不明白为什么你需要两个循环和列表 removeList 当你可以在第一个循环中直接删除元素时
你没有阅读文档 - 在 pykml 库的文档 examples 下很好地描述了如何将对象树写入文件

试试下面的代码：

from lxml import etree
from pykml import parser

kml_file_path = './input.kml'

# parse the input file into an object tree
with open(kml_file_path) as f:
  tree = parser.parse(f)

# get a reference to the "Document.Folder" node
folder = tree.getroot().Document.Folder

# iterate through all "Document.Folder.Placemark" nodes and find and remove all nodes 
# which contain child node "name" with content "ZONE"
for pm in folder.Placemark:
    if pm.name == 'ZONE':
        parent = pm.getparent()
        parent.remove(pm)

# convert the object tree into a string and write it into an output file
with open('output.kml', 'w') as output:
    output.write(etree.tostring(tree, pretty_print=True))

很简单：

KML 文件被解析为对象树并存储在变量 tree
直接操作同一个对象树（去掉元素）
相同的对象树被写回文件

Answer 2

考虑一下 XSLT，设计用于转换 XML 文件的专用语言。并且因为 KML 文件是 XML 文件，所以这个解决方案是可行的。 Python 的第三方模块 lxml 可以运行 XSLT 1.0 脚本，并且无需循环即可执行此操作。

具体来说，XSLT 脚本运行s Identity Transform 可以按原样复制整个文档。然后，脚本运行在元素上创建一个空模板（以特定逻辑为条件）以删除该元素。为了适应默认命名空间，前缀 doc 用于 XPath 搜索。

XSLT （另存为.xsl文件，特殊的.xml文件在下面Python加载）

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                              xmlns:doc="http://earth.google.com/kml/2.2">
    <xsl:output method="xml" indent="yes"/>
    <xsl:strip-space elements="*"/>

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

    <xsl:template match="doc:Placemark[doc:name='ZONE']"/>

</xsl:stylesheet>

XSLT Fiddle Demo

Python

import lxml.etree as et

# LOAD XML AND XSL
doc = et.parse('/path/to/Input.xml')
xsl = et.parse('/path/to/XSLT_Script.xsl')

# CONFIGURE TRANSFORMER
transform = et.XSLT(xsl)    

# RUN TRANSFORMATION
result = transform(doc)

# PRINT RESULT
print(result)  

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

输出

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
   <Document>
      <name>Lombardia</name>
      <Style>
    ...
    </Style>
      <Folder>
         <Placemark>
            <name>ZOGNO</name>
            <styleUrl>#FEATURES_LABELS</styleUrl>
            <Point>
               <coordinates>9.680530595139061,45.7941656233647,0</coordinates>
            </Point>
         </Placemark>
      </Folder>
   </Document>
</kml>

从另一个写入 KML 文件

Write KML file from another

python

python-3.x

data-science

kml

pykml