I am working on XML-Parsing and I want to get the attribute of a sepcific value. I have a XML-file (see bellow) and I want to get the value of val in the second line after lid="diagnosticEcgSpeed" which is -1.
<global>
<setting lid="diagnosticEcgSpeed" val="-1" pers="" res="" unit="mm/s">
<txt id="001041" description="" type="">Geschwindigkeit</txt>
<value lid="1" val="-1" text="50"/>
<value lid="2" val="-2" text="25"/>
<value lid="4" val="-4" text="12,5"/>
<!-- todo: only one value is needed -> use adult value -->
<preset i="-1" c="-1" a="-1" />
</setting>
<setting lid="diagnosticEcgScale" val="10" unit="mm/mV" pers="" res="">
<txt id="001040" description="" type="">Amplitudenskalierung</txt>
<value lid="2" val="2" />
<value lid="5" val="5" />
<value lid="10" val="10" />
<value lid="20" val="20" />
<!-- todo: only one value is needed -> use adult value -->
<preset i="10" c="10" a="10" />
</setting>
</global>
I tried so far this code:
import xml.etree.ElementTree as ET
tree = ET.parse('basics.xml')
root = tree.getroot()
y=root.find(".//*[@lid='diagnosticEcgSpeed']").attrib['val']
print(y)
And the return is
Traceback (most recent call last):
File "parsing_example.py", line 5, in <module>
y=root.find(".//*[@lid='diagnosticEcgSpeed']").attrib['val']
KeyError: 'val'
I don't understand what my error is to get my value var.
CodePudding user response:
You can use the following xpath: .//setting[@lid='diagnosticEcgSpeed']
to retrieve the element and then retrieve its attribute.
See the example below:
data = """
<global>
<setting lid="diagnosticEcgSpeed" val="-1" pers="" res="" unit="mm/s">
<txt id="001041" description="" type="">Geschwindigkeit</txt>
<value lid="1" val="-1" text="50"/>
<value lid="2" val="-2" text="25"/>
<value lid="4" val="-4" text="12,5"/>
<!-- todo: only one value is needed -> use adult value -->
<preset i="-1" c="-1" a="-1" />
</setting>
</global>
"""
import xml.etree.ElementTree as ET
tree = ET.fromstring(data)
y=tree.find(".//setting[@lid='diagnosticEcgSpeed']").attrib["val"]
print(y)
In your case if you want to extract this value directly from a file you can use the following:
import xml.etree.ElementTree as ET
tree = ET.parse('./basics.xml')
y=tree.find(".//setting[@lid='diagnosticEcgSpeed']").attrib['val']
print(y)
Which output:
-1