Python lxml：如何拆分逗号分隔的数据并从 XML 文件中查找特定值？

Question

I have an XML-file containing thousands rows of data. One XML-file looks like this:

<logs xmlns="http://www.xxxxxx.org/xxxxxx/1ser" 
<data> 0.0,1.0,3.0 </data>
<data> 0.5,2.0,4.0 </data>
<data> 1.0,5.0,10.0 </data>
</logs>

I only need to read one specific tag from each file. From the example XML I need only row three and from two values from there (first "column" and the sixth column). Values are comma-separated inside of data -tags. Basically, I need to find and print temperature value based on location, which I already know.

I started with lxml.etree and with the code that prints whole data set:

import lxml.etree as ET
file='data.xml'
tree = ET.parse(file)
root = tree.getroot()
for data in root.iter(data):
    print(data.text)

EDIT1

Once I got an advice to use Xpath and split-method, I have made a piece of code, which looks like this:

import lxml.etree as ET
file='data.xml'
tree = ET.parse(file)
root = tree.getroot()
ns = {'n': 'http://www.xxxxxx.org/xxxxxx/1ser'}
for data in root.xpath('//n:data[contains(text(), "1.0")]', namespaces=ns):
    print(data.text)

This produces output as 1.0,5.0,10.0

Using this method I can search and get the row number three based on the location (1.0 m). However, at the moment I'm not able to split the inner text of tag and I don't know how to do that:

If I try to split above mentioned output like this

datat = data.split(",")

I get attribute error:

AttributeError: 'lxml.etree._Element' object has no attribute 'split'

And I guess this means that lxml has no split -method and I need to figure out another way to do that. If I try to split above mentioned output this way:

datat = [i.split(",") for i in data]
print(datat[0])

My output is just empty brackets meaning that this for loop does most likely nothing. Printing datat gives me this error, which most likely proves that I haven't done it right.

IndexError: list index out of range

My desired output after splitting would be '1.0','5.0','10.0' in order to get my desired output value 10.0 . After split-method, I guess that vale can be just found adding two more lines:

T = float(datat[5])
print(T.text)

Does anyone know what is wrong with my splitting methods? Since I'm not doing it right and haven't yet found any helpful advice via google.

Answer 1

Thanks for the advice related to Xpath and split -method. Finally, I found a solution to get the value I'm looking for:

import lxml.etree as ET
file='data.xml'
tree = ET.parse(file)
root = tree.getroot()
ns = {'n': 'http://www.xxxxxx.org/xxxxxx/1ser'}
for data in root.xpath('//n:data[contains(text(), "1.0")]', namespaces=ns):
        data_string = data.text
        print(data_string)
        split_data = data_string.split(',')
        print(split_data)
        T = float(split_data[2])
        print(T)

Problem seems to be that I didn't create a string. Basically, I was missing one line in my edit section:

data_string = data.text
print(data_string)

with output: 1.0,5.0,10.0 This command splits data:

split_data = data_string.split(',')
print(split_data)

with output: ['\\n1.0', 5.0, 10.0\\n']

And finally this gives me the output I was looking for:

T = float(split_data[2])
print(T)

with output: 10.0