Parsing XML to get one value

[NeillHog]

This is probably so easy that no tutorial anywhere deals with it. Sorry but I just can not find where to start.

I have an XML file as follows
</gpx>
<trk>
<name>070626KappellerAlp</name>
<desc></desc>
<trkseg>
<trkpt lat="47.62788" lon="10.49729">
<ele>876.38</ele>
<time>2007-06-26T14:48:07.000Z</time>
</trkpt>
<trkpt lat="47.62777" lon="10.49757">
<ele>876.38</ele>
<time>2007-06-26T14:48:10.000Z</time>
</trkpt>
</trkseg>
</trk>
</gpx>

The only data I am interested in at the moment is between the <ele> tags. Later I will need others but not yet.

I want to open the file, find the first <ele>, do something with it and then go on to the next <ele> and do it again.
I want to cary on like this until there are no more <ele> left at which point I am finished.

It sounds so easy but for a newbie Python programmer it seems nearly impossible. I have read all about SAX and that seems to be what I need but I am totally confused.

Could one of you experts please spare a few minutes to point me in the correct direction.

Thank you very much in advance.

For any one interested - this is part of a mountain bike track in GPX format and I am aiming at a profiler that calculates climb and descent based on a freely given threshhold.

[Quikee]

from xml.etree import ElementTree

if __name__ == "__main__":
	tree = ElementTree.parse("test.xml")
	root = tree.getroot()
	iter = root.getiterator("ele")
	for i in iter:
		print i.text

But I think this will be more useful to you:

from xml.etree import ElementTree

if __name__ == "__main__":
	tree = ElementTree.parse("test.xml")
	root = tree.getroot()
	trackSegments = root.getiterator("trkseg")
	for trackSegment in trackSegments:
		for trackPoint in trackSegment:
			print trackPoint.attrib['lat']
			print trackPoint.attrib['lon']
			print trackPoint.find('ele').text
			print trackPoint.find('time').text

[slavik]

from xml.etree import ElementTree

if __name__ == "__main__":
	tree = ElementTree.parse("test.xml")
	root = tree.getroot()
	iter = root.getiterator("ele")
	for i in iter:
		print i.text

But I think this will be more useful to you:

from xml.etree import ElementTree

if __name__ == "__main__":
	tree = ElementTree.parse("test.xml")
	root = tree.getroot()
	trackSegments = root.getiterator("trkseg")
	for trackSegment in trackSegments:
		for trackPoint in trackSegment:
			print trackPoint.attrib['lat']
			print trackPoint.attrib['lon']
			print trackPoint.find('ele').text
			print trackPoint.find('time').text

I'd suggest using regex ...

Perl version:

open $file, "test.xml" or die $!;
@array = map { $_ =~ /<ele>(.*?)<\/ele>/ } <$file>;
for $i (@array) {
  print $array[$i] . "\n";
}
close $file;

[aks44]

I'd suggest using regex ...

And accept invalid XML without even blinking?

[Quikee]

I'd suggest using regex ...

Perl version:

open $file, "test.xml" or die $!;
@array = map { $_ =~ /<ele>(.*?)<\/ele>/ } <$file>;
for $i (@array) {
  print $array[$i] . "\n";
}
close $file;

Sorry, but I don't see a single point (except in speed maybe) why this would be better.

[NeillHog]

Hello Quikee!

First thank you. Your code was short and understandable. Exactly what some one like me needs. And it was Python as I asked for

I used your second suggestion on a test xml file (the same as I copied in to the question and "it worked"

Thanks!

I then tried with my "real file" and I get no output.
I have copied the file below. Before I get in to an orgy of debugging - can you tell me which part is stopping the output.

Once again thanks. I love Python and Ubuntu - not because I always understand them but because some kind soul will always help me

<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
<gpx
version="1.1"
creator="Touratech QV 4.0.87 Standard - http://www.ttqv.com"
xmlnssi="http://www.w3.org/2001/XMLSchema-instance" xmlns:topografix="http://www.topografix.com/GPX/Private/TopoGrafix/0/1"
xmlns="http://www.topografix.com/GPX/1/1"
xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
<metadata>
<time>2007-09-02T17:30:53Z</time>
<bounds minlat="47.4481272697449" minlon="10.4949045181274" maxlat="47.6289081573486" maxlon="11.0962772369385"/>
</metadata>
<trk>
<name>070902Garmisch</name>
<cmt>ActiveLog_2007-09-02_001
Download Date: 02.09.2007 19:20:26</cmt>
<trkseg>
<trkpt lat="47.6289081573486" lon="10.4949045181274">
<ele>867</ele>
<time>2007-09-02T06:04:35Z</time>
</trkpt>
</trkseg>
</trk>
<extensions>
</extensions>
</gpx>

[slavik]

And accept invalid XML without even blinking?

In this situation, who cares if you have valid xml if you only care about certain tags?

[aks44]

In this situation, who cares if you have valid xml if you only care about certain tags?

Because if the XML isn't valid then the contents of the tag is probably incorrect as well?

[LaRoza]

Using the DOM is much better than using regex. Now, the contents of the elements can be processed with regex, but this is not some arbitrary string, it an XML file.

[slavik]

Because if the XML isn't valid then the contents of the tag is probably incorrect as well?

or if you haven't downloaded the entire file?

Jabber conversations are continuous XML streams (which causes a problem when one user disconnects)