Python

I am attempting to remove parent XML elements based on the text of specific child elements containing values of “nan”. The input XML contains namespaces which is making this trickier than expected and I can remove select child elements individually, but not the associated/adjacent parent elements. I am only able to remove the “nan” value associated with the gam:String element, but I would like to remove all child elements with “nan” text values and their associated parent elements.

Below is the script I am using, along with the input and (desired) output XMLs….any assistance is most appreciated!

The Script:

from lxml import etree
import os 

path = "C:\users\mdl518\Desktop\"

### Removing "Nan" Values
tree = etree.parse(os.path.join(path,"metadata_info.xml"))

for elem in tree_2.findall('.//{http://standards.iso.org/iso/19115/-3/gam/1.0}String'):
   if elem.text=='nan':
     parent = elem.getparent()
     parent.remove(elem)
    
with open(".//metadata_output.xml","wb") as f:
    f.write(etree.tostring(tree_2, xml_declaration=True, encoding='utf-8')) ## Removes elements with "nan" values

Input XML:

<?xml version='1.0' encoding='utf-8'?>
<nas:metadata xmlns:nas="http://www.arcgis.com/schema/nas/base"   
xmlns:mcc="http://standards.org/iso/19115/-3/mcc/1.0"    
xmlns:mdl="http://standards.org/iso/19115/-3/mdl/1.0" 
xmlns:mnl="http://standards.org/iso/19115/-3/mnl/1.0">
xmlns:lan="http://standards.org/iso/19115/-3/lan/1.0">
xmlns:lis="http://standards.org/iso/19115/-3/lis/1.0">
xmlns:gam="http://standards.org/iso/19115/-3/gam/1.0">
  <mdl:metadataIdentifier>
    <mcc:MD_Identifier>
      <mnl:name>
        <mnl:type>
          <gam:String>The Metadata File</gam:String>
        </mnl:type>
        <mnl:description>
          <mcc:listing codeList="http://arcgis.com/codelist/ScopeCode" codeListValue="dataset"</mcc:listing>
        </mnl:description>
      </mnl:name>
      <mnl:address>
        <mnl:defaultLocale>
          <lan:location>nan</lan:location>
        </mnl:defaultLocale>
      </mnl:address>
      <lan:language>
        <lan:type>
          <lis:name>English</lis:name>
        </lan:type>
       </lan:language>
     </mcc:MD_Identifier>
     <mcc:contactInfo>
       <mdl:POC>
         <mnl:name>
           <lis:person>Tom</lis:person>
         </mnl:name>
         <mnl:age>
           <gam:String>nan</gam:String>
         </mnl:age>
         <mnl:status>
           <lis:employment>nan</lis:employment>
         </mnl:status>
       </mdl:POC>
     </mcc:contactInfo>
   </mdl:metadataIdentifier>
 </nas:metadata>

Output XML:

<?xml version='1.0' encoding='utf-8'?>
<nas:metadata xmlns:nas="http://www.arcgis.com/schema/nas/base"   
xmlns:mcc="http://standards.org/iso/19115/-3/mcc/1.0"    
xmlns:mdl="http://standards.org/iso/19115/-3/mdl/1.0" 
xmlns:mnl="http://standards.org/iso/19115/-3/mnl/1.0">
xmlns:lan="http://standards.org/iso/19115/-3/lan/1.0">
xmlns:lis="http://standards.org/iso/19115/-3/lis/1.0">
xmlns:gam="http://standards.org/iso/19115/-3/gam/1.0">
  <mdl:metadataIdentifier>
    <mcc:MD_Identifier>
      <mnl:name>
        <mnl:type>
          <gam:String>The Metadata File</gam:String>
        </mnl:type>
        <mnl:description>
          <mcc:listing codeList="http://arcgis.com/codelist/ScopeCode" codeListValue="dataset"</mcc:listing>
        </mnl:description>
      </mnl:name>
      <lan:language>
        <lan:type>
          <lis:name>English</lis:name>
        </lan:type>
       </lan:language>
     </mcc:MD_Identifier>
     <mcc:contactInfo>
       <mdl:POC>
         <mnl:name>
           <lis:person>Tom</lis:person>
         </mnl:name>
       </mdl:POC>
     </mcc:contactInfo>
   </mdl:metadataIdentifier>
 </nas:metadata>

Answer

This has to be done in two stages: first remove all nodes with nan text nodes and then go over the empty nodes created by the first step and remove them as well:

#step 1 - remove nan nodes
for n in tree.xpath('//*[.="nan"]'):
    n.getparent().remove(n)]

#step 2 - select empty nodes and remove them as well
empty = [e for e in doc.xpath('//*[not(normalize-space())]')]

for emp in empty:
    try:
        emp.getparent().remove(emp)
    #one nested empty node is created by the first step; this step removes both nodes so try/except is necessary:
    except:
        continue
print(etree.tostring(doc).decode())

This should get you your desired output.

Remove XML Parent Elements Based on Condition of Child Element – Python

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Answer