How to structure the data using webread
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Hi, I will have to automatize a procedure to extract data from different URLs, One example of the URL link is the following:
url='https://earthquake.usgs.gov/fdsnws/event/1/query?format=quakeml&eventid=us6000n8tq',
data=webread(url);
The variable data has a huge amount of information that I would like to structure in order to access and retrieve the data easily without the need of creating a xml file.
I would appreciate the help.
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Accepted Answer
Ayush Aniket
on 16 Jul 2024
Edited: Ayush Aniket
on 16 Jul 2024
Hi Jorge,
To retrieve specific data from the XML file, you can use regexp on the string output of webread function. Refer the following MATLAB answer for an example: https://www.mathworks.com/matlabcentral/answers/883153-how-to-extract-the-data-from-webread-output
You may also refer the following link to understand more about the regexp function: https://www.mathworks.com/matlabcentral/answers/402062-help-using-regexp?#answer_321487
More Answers (1)
Anshuman
on 16 Jul 2024
First you can parse the data to xmlData:
% Convert the data from char to XML DOM
xmlData = xmlreadstring(data);
You can use XPath queries to extract specific elements from the XML data:
% Create an XPath factory and compile the XPath expression
factory = javax.xml.xpath.XPathFactory.newInstance;
xpath = factory.newXPath;
% Extract magnitude
magnitudeExpression = xpath.compile('//magnitude/mag/value');
magnitudeNode = magnitudeExpression.evaluate(xmlData, javax.xml.xpath.XPathConstants.NODE);
magnitude = str2double(magnitudeNode.getTextContent);
This way you can extract the specific data like magnitude and any other information as needed.
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