Skip to content

Instantly share code, notes, and snippets.

@Ram-N Ram-N/books.xml
Last active Apr 3, 2019

What would you like to do?
This is a sample XML file that Microsoft makes available.
<?xml version="1.0"?>
<book id="bk101">
<author>Gambardella, Matthew</author>
<title>XML Developer's Guide</title>
<description>An in-depth look at creating applications
with XML.</description>
<book id="bk102">
<author>Ralls, Kim</author>
<title>Midnight Rain</title>
<description>A former architect battles corporate zombies,
an evil sorceress, and her own childhood to become queen
of the world.</description>
<book id="bk103">
<author>Corets, Eva</author>
<title>Maeve Ascendant</title>
<description>After the collapse of a nanotechnology
society in England, the young survivors lay the
foundation for a new society.</description>
<book id="bk104">
<author>Corets, Eva</author>
<title>Oberon's Legacy</title>
<description>In post-apocalypse England, the mysterious
agent known only as Oberon helps to create a new life
for the inhabitants of London. Sequel to Maeve
<book id="bk105">
<author>Corets, Eva</author>
<title>The Sundered Grail</title>
<description>The two daughters of Maeve, half-sisters,
battle one another for control of England. Sequel to
Oberon's Legacy.</description>
<book id="bk106">
<author>Randall, Cynthia</author>
<title>Lover Birds</title>
<description>When Carla meets Paul at an ornithology
conference, tempers fly as feathers get ruffled.</description>
<book id="bk107">
<author>Thurman, Paula</author>
<title>Splish Splash</title>
<description>A deep sea diver finds true love twenty
thousand leagues beneath the sea.</description>
<book id="bk108">
<author>Knorr, Stefan</author>
<title>Creepy Crawlies</title>
<description>An anthology of horror stories about roaches,
centipedes, scorpions and other insects.</description>
<book id="bk109">
<author>Kress, Peter</author>
<title>Paradox Lost</title>
<genre>Science Fiction</genre>
<description>After an inadvertant trip through a Heisenberg
Uncertainty Device, James Salway discovers the problems
of being quantum.</description>
<book id="bk110">
<author>O'Brien, Tim</author>
<title>Microsoft .NET: The Programming Bible</title>
<description>Microsoft's .NET initiative is explored in
detail in this deep programmer's reference.</description>
<book id="bk111">
<author>O'Brien, Tim</author>
<title>MSXML3: A Comprehensive Guide</title>
<description>The Microsoft MSXML3 parser is covered in
detail, with attention to XML DOM interfaces, XSLT processing,
SAX and more.</description>
<book id="bk112">
<author>Galos, Mike</author>
<title>Visual Studio 7: A Comprehensive Guide</title>
<description>Microsoft Visual Studio 7 is explored in depth,
looking at how Visual Basic, Visual C++, C#, and ASP+ are
integrated into a comprehensive development
# @ramnarasimhan
# for additional help please refer to :
#Recursive Function to visit the XML tree (depth first)
visitNode <- function(node) {
if (is.null(node)) {
#leaf node reached. Turn back
print(paste("Node: ", xmlName(node)))
num.children = xmlSize(node)
if(num.children == 0 ) {
# Add your code to process the leaf node here
print( paste(" ", xmlValue(node)))
#Go one level deeper
for (i in 1 : num.children) {
visitNode(node[[i]]) #the i-th child of node
xmlfile <- "books.xml"
#read the XML tree into memory
xtree <- xmlInternalTreeParse(xmlfile)
root <- xmlRoot(xtree)

This comment has been minimized.

Copy link

commented Jul 20, 2016

Hi Ram,
I have tried your code but was given an error message:
Error in [[.XMLInternalElementNode(node, i) :
cannot index an internal node with a negative number -1

Could you help please?


This comment has been minimized.

Copy link

commented Jan 4, 2017

Tilly - wrap the "one level deeper" statement in a conditional:

if (num.children > 0) { 
  for (i in 1 : num.children) { 
    visitNode(node[[i]]) #the i-th child of node 
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.