How to structure the data using webread

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Jorge Luis 2024-7-15，12:12

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https://ww2.mathworks.cn/matlabcentral/answers/2137353-how-to-structure-the-data-using-webread

编辑： Jorge Luis 2024-7-17，18:08

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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Answer 1

Ayush Aniket 2024-7-16，5:25

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https://ww2.mathworks.cn/matlabcentral/answers/2137353-how-to-structure-the-data-using-webread#answer_1485913

编辑：Ayush Aniket 2024-7-16，5:55

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

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Jorge Luis 2024-7-16，7:54

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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Answer 2

Anshuman 2024-7-16，8:38

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https://ww2.mathworks.cn/matlabcentral/answers/2137353-how-to-structure-the-data-using-webread#answer_1486058

在 MATLAB Online 中打开

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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Jorge Luis 2024-7-16，21:54

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 2024-7-17，17:56