Question

我正在尝试：

- 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>

问题在于，当我编写新的KML文件时，它仍然具有我要删除的元素。实际上，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

考虑XSLT，一种专用于转换XML文件的专用语言。而且由于KML文件是 XML文件，因此该解决方案是可行的。 Python的第三方模块lxml可以运行XSLT 1.0脚本，并且无需单个循环即可运行。

具体来说，XSLT脚本运行Identity Transform以照原样复制整个文档。然后，脚本在元素上运行一个空模板（取决于特定逻辑）以删除该元素。为了容纳默认的名称空间，前缀 doc 用于XPath搜索。

XSLT （另存为.xsl文件，这是一个特殊的.xml文件，将在下面的Python中加载）

<?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>

Answer 2

您的代码中存在以下问题：

您不会将整个已分析的对象树存储在任何位置（您仅引用了节点“ Document.Folder ”：folder = parser.parse(f).getroot().Document.Folder），但您想将其写回到文件，因此您需要存储
我不明白为什么可以在第一个循环中直接删除元素时需要两个循环和列表removeList
您不阅读文档-很好地描述了如何将对象树写入pykml库文档中examples下的文件中

尝试以下代码：

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))

这很简单：

KML文件被解析为对象树，并存储在变量tree
直接操纵同一对象树（删除的元素）
同一对象树被写回到文件中

从另一个写入KML文件

2 个答案: