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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.

Accepted Answer

Ayush Aniket
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
  1 Comment
Jorge Luis
Jorge Luis on 16 Jul 2024
Thank you very much. Yes, that was the other option I was tempted to use but considering all the amount of data, I wanted a way in which all the information is converted in a structure matrix. I managed to do that but you need to save the data and use functions to write a xlm file and then structure the file.

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More Answers (1)

Anshuman
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.
  2 Comments
Jorge Luis
Jorge Luis on 16 Jul 2024
Much appreciated. I am still looking for the way of saving the files as xlm witouth saving the webread data in order to structure all the information using the following function: https://www.mathworks.com/matlabcentral/fileexchange/28639-struct2xml.
Jorge Luis
Jorge Luis on 17 Jul 2024
The function xmlreadstring does not work.

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