I am looking to edit XML files using python. I want to find and replace keywords in the tags. In the past, a co-worker had set up template XML files and used a "find and replace" program to replace these key words. I want to use python to find and replace these key words with values. I have been teaching myself the Elementtree module, but I am having trouble trying to do a find and replace. I have attached a snid-bit of my XML file. You will seen some variables surrounded by % (ie %SITEDESCR%) These are the words I want to replace and then save the XML to a new file. Any help or suggestions would be great.

Thanks, Mike

<metadata>
<idinfo>
<citation>
<citeinfo>
 <origin>My Company</origin>
 <pubdate>05/04/2009</pubdate>
 <title>POLYGONS</title>
 <geoform>vector digital data</geoform>
 <onlink>\\C$\ArcGISDevelopment\Geodatabase\PDA_STD_05_25_2009.gdb</onlink>
</citeinfo>
</citation>
 <descript>
 <abstract>This dataset represents the mapped polygons developed from the field data for the %SITEDESCR%.</abstract>
 <purpose>This dataset was created to accompany some stuff.</purpose>
 </descript>
<timeperd>
<timeinfo>
<rngdates>
 <begdate>%begdate%</begdate>
 <begtime>unknown</begtime>
 <enddate>%enddate%</enddate>
 <endtime>unknown</endtime>
 </rngdates>
 </timeinfo>
 <current>ground condition</current>
 </timeperd>

The basics:

from xml.etree import ElementTree as et
tree = et.parse(datafile)
tree.find('idinfo/timeperd/timeinfo/rngdates/begdate').text = '1/1/2011'
tree.find('idinfo/timeperd/timeinfo/rngdates/enddate').text = '1/1/2011'
tree.write(datafile)

You can shorten the path if the tag name is unique. This syntax finds the first node at any depth level in the tree.

tree.find('.//begdate').text = '1/1/2011'
tree.find('.//enddate').text = '1/1/2011'

Also, read the documentation, esp. the XPath support for locating nodes.