How to remove several lines in xml file and then save it in Python

I want to remove all lines that contain all words in the 'xml_lines' list. I created this script:

from pathlib import Path

# Provide relative or absolute file path to your xml file
filename = './.content.xml'
path = Path(filename)

conntents = path.read_text()

xml_lines = [
    'first',
    'second',
]

lines = conntents.splitlines()

removed_lines = 0

for line in lines:
    for xml_line in xml_lines:
        if xml_line in line:
            lines.remove(line)
            removed_lines += 1
            print(f'Line: "{line.strip()}" has been removed!')

print(f"\n\n{removed_lines} lines have been removded!")

path.write_text(str(lines))

At the and I have a file that does not look like xml. Can anyone help?

Example (before):

<?xml version="1.0"?>
<data>
    <country
        name="Liechtenstein"
        first="2d2md"
        second="m3d39d93">
            <rank updated="yes">2</rank>
            <year>2008</year>
            <gdppc>141100</gdppc>
            <neighbor name="Austria" direction="E"/>
            <neighbor name="Switzerland" direction="W"/>
    </country>
    <tiger
        name="Singapore"
        first="hfdfherbre"
        second="m3d39d93">
            <rank updated="yes">5</rank>
            <year>2011</year>
            <gdppc>59900</gdppc>
            <neighbor name="Malaysia" direction="N"/>
    </tiger>
    <car
        name="Panama"
        first="th54b4"
        second="45b45gt45h">
            <rank updated="yes">69</rank>
            <year>2011</year>
            <gdppc>13600</gdppc>
            <neighbor name="Costa Rica" direction="W"/>
            <neighbor name="Colombia" direction="E"/>
    </car>
</data>

if script finds any line that contain 'first' or 'second', the entire line should be removed:

<?xml version="1.0"?>
<data>
    <country
        name="Liechtenstein"
        >
            <rank updated="yes">2</rank>
            <year>2008</year>
            <gdppc>141100</gdppc>
            <neighbor name="Austria" direction="E"/>
            <neighbor name="Switzerland" direction="W"/>
    </country>
    <tiger
        name="Singapore"
        >
            <rank updated="yes">5</rank>
            <year>2011</year>
            <gdppc>59900</gdppc>
            <neighbor name="Malaysia" direction="N"/>
    </tiger>
    <car
        name="Panama">
        >
            <rank updated="yes">69</rank>
            <year>2011</year>
            <gdppc>13600</gdppc>
            <neighbor name="Costa Rica" direction="W"/>
            <neighbor name="Colombia" direction="E"/>
    </car>
</data>

This is only an example, entire xml file consists of 9999999 lines...

Consider XSLT the special-purpose language designed to transform XML files. Specifically, an identity template and empty template can remove the needed attributes across entire document without a single for loop. Python's lxml third-party package can run XSLT 1.0 scripts.

XSLT (save as .xsl file, a special XML file)

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" encoding="utf-8" indent="yes"/>
    <xsl:strip-space elements="*"/>
    
    <!-- IDENTITY TRANSFORM -->
    <xsl:template match="@* | node()">
        <xsl:copy>
            <xsl:apply-templates select="@* | node()"/>
        </xsl:copy>
    </xsl:template>

    <!-- EMPTY TEMPLATE TO REMOVE CONTENT -->
    <xsl:template match="@first|@second"/>
</xsl:stylesheet>

<kbd>Online Demo</kbd>

Python

import lxml.etree as lx

# PARSE XML AND XSLT
doc = lx.parse("Input.xml")
style = lx.parse("Style.xsl")

# CONFIGURE AND RUN TRANSFORMER
transformer = lx.XSLT(style)
result = transformer(doc)

# OUTPUT TO FILE
result.write_output("Output.xml")

You could do something simple along the lines described in this answer, basically using xpath and lxml (and there may be other ways to do the same):

from lxml import etree
doc = etree.parse("your xml file")

to_drop = ["first","second"]
for td in to_drop:
    for target in doc.xpath('//*'):
        target.attrib.pop(td, None)
print(etree.tostring(doc).decode())

Output should be your expected output.

For huge xml files you can use iterparse() and manipulate the attribute values:

import xml.etree.ElementTree as ET

filename = "outfile.xml"
with open(filename, 'wb') as out:
    out.write(str.encode('<?xml version="1.0"?>\n<data>\n'))

attrib_list = ['first','second']

def removekey(d, keys):
    r = dict(d)
    for key, value in keys.items():
        del r[key]
    return r

for event, elem in ET.iterparse("pop_del.xml", events=("start","end")):
    n = {k: elem.attrib[k] for k in elem.attrib.keys() & set(attrib_list)}
    if len(n) != 0:
        elem.attrib = removekey(elem.attrib, n)
        with open("outfile.xml", 'ab') as out:
            out.write(ET.tostring(elem))
            
with open(filename, 'ab') as out:
    out.write(str.encode('</data>'))

Output:

<?xml version="1.0"?>
<data>
  <country name="Liechtenstein">
    <rank updated="yes">2</rank>
    <year>2008</year>
    <gdppc>141100</gdppc>
    <neighbor name="Austria" direction="E" />
    <neighbor name="Switzerland" direction="W" />
  </country>
  <tiger name="Singapore">
    <rank updated="yes">5</rank>
    <year>2011</year>
    <gdppc>59900</gdppc>
    <neighbor name="Malaysia" direction="N" />
  </tiger>
  <car name="Panama">
    <rank updated="yes">69</rank>
    <year>2011</year>
    <gdppc>13600</gdppc>
    <neighbor name="Costa Rica" direction="W" />
    <neighbor name="Colombia" direction="E" />
  </car>
</data>

You can use pop() or del() to remove a attribute from tag element.