The code below is written as part of a parser, which files would be also added here: XMLParser, parser, Name, GenericElement, attrib

It reads an XML files from a folder, turn them into a dataframe using pandas and then parse it into a CSV file.

from generic_parser import XMLParser
import pandas as pd
import os

opdatas = []
df = pd.DataFrame()
tags_to_leave = ['Description', 'FileX', 'FileY']
value_data = ['SetData']

def dropper(obj):
    return obj.name not in tags_to_leave + value_data, True

def opdata_collector(obj):
    cnt = 0
    global df
    if obj.name == 'START':
        obj = rename_attribs(obj)
        # opdatas.append(obj)
        final_dict = dict(obj.attribs)
        # final_dict.update({'ValueData' : []})
        value_data_dict = {}
        for child in obj.children:
            if str(child.name) in tags_to_leave:
            if str(child.name) in value_data:
                for key_name in child.attribs.keys():
                    final_dict['SetData' + key_name + str(cnt)] = child.attribs[key_name]
                cnt += 1

        df = df.append(final_dict, ignore_index=True)

def rename_attribs(obj):
    if str(obj.name) == 'Description':
        obj.attribs["text"] = obj.text
    obj.attribs.sub_keys(r"^(.*)$", str(obj.name) + r"_\1")
    return obj

if __name__ == '__main__':
    #xml = XMLParser.parse(r'./work.xml')
    directory= 'C:/Users/232/Desktop/32/Files/test'
    for filename in os.listdir(directory):
        if filename.endswith(".xml"):

This is the XML file

  <?xml version="1.0" encoding="utf-8"?>
    <START id="DG0003" service_code="0x517B">
      <Docs Docs_type="START">
      <Description num="3423423f3423">The third</Description>
      <SetFile dg="" dg_id="">
        <FileX dg="" axis_pts="2" name="" num="" dg_id="" />
        <FileY tint="" axis_pts="20" name="TOOLS" num="23423" tint_id="" />
        <SetData x="E1" value="21259" />
        <SetData x="E2" value="0" />
    <START id="ID0048" service_code="0x5198">
      <Docs Docs_type="START">
        <Quality >343243324234234</Quality >
      <Description num="434234234">The forth</Description>
      <Normal tint="m" tint_id="FEDS">
        <FileX be="dssad" get="false" axis_pts="19" name="asdas" num="SDF3" tint_id="SDGFDS" />
        <SetData xin="sdf" xax="233" value="323" />
        <SetData xin="123" xax="213" value="232" />
        <SetData xin="2321" xax="232" value="23" />
        <SetData xin="-inf" xax="45" value="423" />
        <SetData xin="234" xax="3" value="4523" />
        <SetData xin="324" xax="423" value="6456234" />
        <SetData xin="30" xax="45234" value="34532" />
        <SetData xin="5345" xax="2345" value="453" />
        <SetData xin="234" xax="345" value="4543" />
        <SetData xin="2321" xax="2345" value="45" />
        <SetData xin="3423432" xax="34" value="453" />
        <SetData xin="21" xax="34" value="45" />
        <SetData xin="12" xax="34" value="345" />
        <SetData xin="43" xax="423" value="7" />
        <SetData xin="64" xax="32" value="0" />
        <SetData xin="434" xax="254" value="5" />
        <SetData xin="343" xax="322" value="3" />
        <SetData xin="36" xax="2" value="0" />
        <SetData xin="23" xax="done" value="0" />

The code works fine however the speed is not optimal. It takes quite some time to parse multiple XML files into one CSV.

The screenshot below shows the output file (I just removed the data for personal reasons). The columns show how the data is distributed

enter image description here

  • 2
    \$\begingroup\$ Looks like your story stackoverflow.com/questions/59269185/… relied on if obj.name == 'START', not on if obj.name == 'OPDATA' as well as your xml content points to that. Would you update the code? \$\endgroup\$ Commented Dec 12, 2019 at 18:49
  • \$\begingroup\$ I fixed the xml file now. Today I tried the code with around 5 xml files that have same structure and it took a long time until it got parsed into a csv file \$\endgroup\$
    – ebe
    Commented Dec 12, 2019 at 22:36
  • 2
    \$\begingroup\$ Could you provide a broad overview of your program? GenericElement mentions something about EXAM, is that relevant/important here? My first thought when I hear XML and speed is not optimal is "lxml". \$\endgroup\$
    – AMC
    Commented Dec 12, 2019 at 23:37
  • \$\begingroup\$ Your tags_to_leave list doesn't refer to anything that's in the xml you've included. Can you also give a small sample csv output? \$\endgroup\$
    – C.Nivs
    Commented Dec 13, 2019 at 4:16
  • \$\begingroup\$ And there is still no "OPDATA" in the XML file, so your parsing will do nothing. Also, you are always adding to the global df, which means that each written CSV contains the content of all parsed XML files that came before, not just the one you are currently parsing. No wonder this is slow. \$\endgroup\$
    – Graipher
    Commented Dec 13, 2019 at 11:37

1 Answer 1


An easy speed-up is not using a global object that you continually modify. This is especially important since you also save the output file over and over, which is completely unnecessary (unless you care about the current state if you abort the program).

from itertools import chain
from pathlib import Path

def opdata_collector(obj):
    if obj.name != 'START':
        return {}
    count = 0
    obj = rename_attribs(obj)
    final_dict = dict(obj.attribs)
    for child in obj.children:
        if str(child.name) in tags_to_leave:
        elif str(child.name) in value_data:
            final_dict.update({f"ValueData{key_name}{count}": value
                               for key_name, value in child.attribs.items()})
            count += 1
    return final_dict

if __name__ == '__main__':
    directory = Path('C:/Users/z647818/Desktop/Erdi/Files/test')
    data = (XMLParser.parse(directory / file_name).recurs_collect(opdata_collector)
            for file_name in os.listdir(directory)
            if file_name.endswith(".xml"))
    df = pd.DataFrame(chain.from_iterable(data))

On top of that the actual opdata_collector can probably also be improved, but this should give you a nice boost.

I also removed unneeded lines, used a dictionary comprehension in the inner loop, turned the if into an elif (you probably don't want a tag to be processed twice), spelled out count (no need to conserve bytes), used an f-string instead of string addition and packed the dataframe generation in one big generator expression.

  • \$\begingroup\$ thank you a lot for your answer. I added the code of mine and the part from your answer and it can be seen HERE but I'm getting AttributeError: 'Attribs' object has no attribute 'items' \$\endgroup\$
    – ebe
    Commented Dec 17, 2019 at 19:59
  • \$\begingroup\$ @ebe I tried it with the file you gave. I'll check again tomorrow if the latest version still works for me. \$\endgroup\$
    – Graipher
    Commented Dec 17, 2019 at 20:02
  • \$\begingroup\$ I have updated the data and also have added a screenshot on how the output looks like(I just removed the data for confidential reasons). It takes a couple of minutes when I run it for 3 xml files. The plan is to use many many more xml and at the current speed of my code it is just not possible. \$\endgroup\$
    – ebe
    Commented Dec 18, 2019 at 14:35
  • \$\begingroup\$ would really appreciate it, if you can have a look at the added part in the question and the comment above. Your code as it for not only has given me a column of numbers and nothing else \$\endgroup\$
    – ebe
    Commented Dec 19, 2019 at 7:59

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