<p>I invested some time into learning R and would prefer not to learn Python or Ruby just for convenience of parsing XML.</p>

<p>I am not a pro R programmer so I need a higher level library then XML package of R.
getNodeSet and XPath is very hard to use.</p>

<p>As for biophyton and bioperl counterpart in R you can use Bioconductor, however it may not have all the functionality you find in those libraries, and bioconductor is the project, you would need to search in biconductor's website for specific packages.</p>