parse data from xml using python 3

You can get the sets directly using https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.ElementTree.Element.findall and xpath (like : 'node_a.node_b.etc.req_node') like shown below code... (also can access the comment text)

import xml.etree.ElementTree as ET
import pandas as pd
from matplotlib import pyplot as plt

tree = ET.fromstring("test.xml")
root = tree.getroot()


for elem in root.findall('./dos/partial/array/set/set/set'):
    comment = elem.get('comment')
    print(comment)
    data = list()
    for row in elem.findall('r'):
        data.append(list(map(float, row.text.split())))
    df = pd.DataFrame(data)
    print(df)
    df.plot()
    plt.show()