Parsing of xml in Python

Question

I am having issue parsing an xml result using python. I tried using etree.Element(text), but the error says Invalid tag name. Does anyone know if this is actually an xml and any way of parsing the result using a standard package? Thank you!

import requests, sys, json
from lxml import etree
response = requests.get("https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=snp&id=1593319917&report=XML")

text=response.text
print(text)

<?xml version="1.0" ?>
<ExchangeSet xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xmlns="https://www.ncbi.nlm.nih.gov/SNP/docsum" xsi:schemaLocation="https://www.ncbi.nlm.nih.gov/SNP/docsum ftp://ftp.ncbi.nlm.nih.gov/snp/specs/docsum_eutils.xsd" ><DocumentSummary uid="1593319917"><SNP_ID>1593319917</SNP_ID><ALLELE_ORIGIN/><GLOBAL_MAFS><MAF><STUDY>SGDP_PRJ</STUDY><FREQ>G=0.5/1</FREQ></MAF></GLOBAL_MAFS><GLOBAL_POPULATION/><GLOBAL_SAMPLESIZE>0</GLOBAL_SAMPLESIZE><SUSPECTED/><CLINICAL_SIGNIFICANCE/><GENES><GENE_E><NAME>FLT3</NAME><GENE_ID>2322</GENE_ID></GENE_E></GENES><ACC>NC_000013.11</ACC><CHR>13</CHR><HANDLE>SGDP_PRJ</HANDLE><SPDI>NC_000013.11:28102567:G:A</SPDI><FXN_CLASS>upstream_transcript_variant</FXN_CLASS><VALIDATED>by-frequency</VALIDATED><DOCSUM>HGVS=NC_000013.11:g.28102568G&gt;A,NC_000013.10:g.28676705G&gt;A,NG_007066.1:g.3001C&gt;T|SEQ=[G/A]|LEN=1|GENE=FLT3:2322</DOCSUM><TAX_ID>9606</TAX_ID><ORIG_BUILD>154</ORIG_BUILD><UPD_BUILD>154</UPD_BUILD><CREATEDATE>2020/04/27 06:19</CREATEDATE><UPDATEDATE>2020/04/27 06:19</UPDATEDATE><SS>3879653181</SS><ALLELE>R</ALLELE><SNP_CLASS>snv</SNP_CLASS><CHRPOS>13:28102568</CHRPOS><CHRPOS_PREV_ASSM>13:28676705</CHRPOS_PREV_ASSM><TEXT/><SNP_ID_SORT>1593319917</SNP_ID_SORT><CLINICAL_SORT>0</CLINICAL_SORT><CITED_SORT/><CHRPOS_SORT>0028102568</CHRPOS_SORT><MERGED_SORT>0</MERGED_SORT></DocumentSummary>
</ExchangeSet>

Your xml is valid. Please show the code to read the xml and error message. — Daniel
– Daniel, Commented May 3, 2021 at 11:19

larsks · Accepted Answer · 2021-05-03 11:22:44Z

You're using the wrong method to parse your XML. The etree.Element class is for creating a single XML element. For example:

>>> a = etree.Element('a')
>>> a
<Element a at 0x7f8c9040e180>
>>> etree.tostring(a)
b'<a/>'

As Jayvee has pointed how, to parse XML contained in a string you use the etree.fromstring method (to parse XML content in a file you would use the etree.parse method):

>>> response = requests.get("https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=snp&id=1593319917&report=XML")
>>> doc = etree.fromstring(response.text)
>>> doc
<Element {https://www.ncbi.nlm.nih.gov/SNP/docsum}ExchangeSet at 0x7f8c9040e180>
>>>

Note that because this XML document sets a default namespace, you'll need properly set namespaces when looking for elements. E.g., this will fail:

>>> doc.find('DocumentSummary')
>>>

But this works:

>>> doc.find('docsum:DocumentSummary', {'docsum': 'https://www.ncbi.nlm.nih.gov/SNP/docsum'})
<Element {https://www.ncbi.nlm.nih.gov/SNP/docsum}DocumentSummary at 0x7f8c8e987200>

Jayvee · Accepted Answer · 2021-05-03 10:52:08Z

0

You can check if the xml is well formed by try converting it:

import requests, sys, json
from lxml import etree
response = requests.get("https://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=snp&id=1593319917&report=XML")

text=response.text 
try:
    doc=etree.fromstring(text)
    print("valid")
except:
    print("not a valid xml")

answered May 3, 2021 at 10:52

Jayvee

10.9k3 gold badges35 silver badges43 bronze badges

Collectives™ on Stack Overflow

Parsing of xml in Python

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related