Comments on: Undocumented XML functionality

By: Yair Altman

Yair Altman — Thu, 02 Feb 2012 00:47:54 +0000

@James – I don’t have an immediate answer for you, it requires some investigation. This sounds like a good idea for a future article. If you cannot wait for this article to appear, you could contact me by email (link at the top right of this page) to discuss a short consulting gig.

By: James Myatt

James Myatt — Wed, 01 Feb 2012 12:10:10 +0000

@Yair, That certainly sounds like a better idea, but I’m not sure how to proceed. Could you indicate how to modify the parseXML function from the xmlread help so that it used the SAX parser rather than the DOM returned by xmlread? Or am I on the wrong track?

By: Yair Altman

Yair Altman — Mon, 30 Jan 2012 22:42:18 +0000

@James – DOM is normally used for small XML models; SAX is usually better for large models that can be processed sequentially. There are numerous SAX parsers available online that you can use in Matlab. Perhaps the most widely used open-source XML parser, which includes support fro both SAX and DOM, is Xerces, which is already pre-bundled in Matlab (take a look at the %matlabroot%/java/jarext/ folder), so you can use it in Matlab out-of-the-box. Other well-known XML support packages, namely Xalan and Saxon, are also pre-bundled.

By: James Myatt

James Myatt — Mon, 30 Jan 2012 21:46:58 +0000

xmlread does a great job of parsing an XML file, but I’ve found that actually extracting data from the DOM hierarchy is pretty slow. For example, the parseXML function in the xmlread help takes about 250 times longer than the call to xmlread itself and vast majority of that time is spent interrogating the DOM objects.

Do you have any suggestions?

By: Yair Altman

Yair Altman — Sat, 21 Nov 2009 16:36:23 +0000

Here’s a nicer “pretty-print”, which uses the undocumented InputSource input argument format of xlswrite:

fReader=java.io.FileReader(java.io.File(which('info.xml')));
xmlwrite(org.xml.sax.InputSource(fReader))

By: Donn Shull

Donn Shull — Fri, 20 Nov 2009 17:58:22 +0000

Hi Yair,

It seems that many people follow an unusal convention for the format of their xml files. Even The MathWork’s info.xml files don’t following the standard indented form for xml files. A quick way to “pretty print” an xml file is to use saveXML method of the DOM node ie:

x = xmlread(which('info.xml'));
x.saveXML(x.getDocumentElement)

Thanks for the good work,

Donn