Change the value of a parameter in xml file using matlab

I have xml file and want to change a value of a parameter inside it. The line that has that specific parameter is:

<variable id="MIG" value="3" description="Change in MIG" />

I want to change value from 3 to other number.

I found these functions to read and write xml file:

DOMnode = xmlread('parameter.xml');

xmlwrite('newparameter.xml',DOMnode);

but not sure how to change the value of variable called "MIG".

Answer 1

[Abhilash Padma]

To change the value of a parameter in an element, along with xmlread and xmlwrite, we need to use getElementsByTagName and setAttribute methods. See the following code where I have changed the value of parameter “value”.

test.xml

<variable id="MIG" value="3" description="Change in MIG" />

xDoc=xmlread(fullfile(('test.xml')));
allListItems=xDoc.getElementsByTagName('variable');
thisListItem=allListItems.item(0);
thisListItem.setAttribute('value','20');
 

Refer the following link for more information: https://in.mathworks.com/help/matlab/import_export/importing-xml-documents.html

Answer 2

[Robert Ungi]

A more general way to do so is

% <?xml version="1.0" encoding="utf-8"?>
% <xml>
%    <busStop endPos="30" id="BusStop0" lane="1to2_0" startPos="20"/>
%     <busStop endPos="80" id="BusStop1" lane="1to2_0" startPos="70"/>
%     <chargingStation chrgPower="220" endPos="30" id="ChrgStn1" lane="1to2_0" startPos="45"/>
% </xml>

import javax.xml.xpath.*

factory = XPathFactory.newInstance;
import javax.script.ScriptContext;
xpath = factory.newXPath;

fXML=xmlread('SampleXML.xml');

expression = xpath.compile('xml/chargingStation[@id="ChrgStn1"]');
chargingStation = expression.evaluate(fXML, XPathConstants.NODESET);


for i=0:chargingStation.getLength-1
    chargingStation.item(i).setAttribute('startPos', "45")        
end

xmlwrite('SampleXMLOut.xml', fXML);

Adopted from The Wizzart.