Category Archives: technology

Off the rails: mag-lev personal rapid transit

I have not been thinking about blog posts much over the last week and a half: on the 11 August my closest friend died and his memorial service was a week later. However, I have received a guest post from a new contributor to the Stubborn Mule: Norwegian academic Trond Andresen from the Norwegian University of Science and Technology. I met Trond last year at the CofFEE conference in Newcastle where he was spending time pursuing his research interests in macroeconomics. However, as will become evident in the post below, Trond also has other rather different academic interests and was inspired by the recent Train in Vain post, to write about a rather radical alternative to high-speed rail.

I am a Norwegian control systems lecturer recently back from a ten-month sabbatical in Newcastle. I have had one-year stays in Australia on two earlier occasions. My first stint was in Sydney 1997-98. I then experienced the city’s grave congestion and environmental problems due to car traffic. Thirteen years later it is even worse.

I have also tried the very slow railway service between Newcastle and Sydney. It hasn’t improved either. From 1997 I remember the debates about intercity high-speed rail and magnetic levitation trains. But this didn’t lead to anything.

Today however, there exists a new and proven – but largely unknown – technology that in one go can solve both the in-city and intercity transportation problems, and it is much cheaper than high-speed rail. That technology is maglev-based personal rapid transit (M-PRT). Computer-controlled small two-person streamlined pods run on a guideway six meters above gound. The guideway is carried by utility poles. The structure is very slender and much less intrusive than the Sydney monorail, because each pod weighs maximum 300 kg. It may be quickly erected along some main thoroughfares, and gradually extended to create a dense city network. One will not anymore depend on a few large stations, but can instead access the system at any of the many hundreds of network nodes (resembling elevated bus stops) you will have in a city like Sydney. A pod hangs under the guideway, and slides along it without wheels and no contact; an extension of the pod inside the guideway levitates it by magnetic repulsion. This is a new, simpler and cheaper type of maglev technology than that used in the very expensive German Transrapid, which was part of the Australian debate in 1997.

Maglev and the absence of wheels give two crucial advantages: very low maintenance requirements, and speeds up to 240 km/h (pods will of course cruise at a much slower speed in a dense city). This translates to impressive intercity timesL Newcastle-Sydney 0:45, Katoomba-Sydney 0:30. Canberra-Sydney 1:30. And between cities you don’t need to travel via central stations, you go directly and nonstop from suburb to suburb. Erecting lines between cities and towns is easy and fast because very little is needed in the way of earthworks: the guideway is on poles 6 meters above the ground. Nature is left largely undisturbed, and traffic and animals may cross freely under the track.

A bidirectional M-PRT line has the same capacity as a freeway with three lanes in each direction (like the new M2). Since there are no chauffeurs needed in the system, tickets may be quite cheap. And energy use per person even at top speed is low, on a par with high speed rail.

This technology should be included in the ongoing discussions. It is far superior to the alternatives.

I research and write about this in cooperation with the  American inventor, Doug Malewicki. But my engagement in this technology is purely academic: while I am the Norwegian contact for SkyTran, which currently has a research agreement with NASA to develop the concept, I have no commercial ties to the company.

Note that this is not Sci-Fi, or eccentric dreaming from some “futurist”. All parts of the system have proved to work, and you might check out the first “flight” of a full-size prototype at NASA’s Ames center, downloadable from here (my uni web site in Norway, guaranteed virus free!).

I gave a talk about the system at Sydney University’s Institute of Transport and Logistics Studies early this year, see presentation here (you find it as the second entry from the top). I was also interviewed about this on the ABC Science Show In spite of these openings, it is really an uphill battle to get radical new solutions out there in the public domain. I tried several times during my Australian stay to get something into the Sydney Morning Herald, but they didn’t even respond.


Last year I wrote about one of the more amusingly ridiculous attempted spam comments intercepted by my blog’s spam filter. It may be genius, stupidity or just an excellent coincidence, but a comment spammer has now attempted to add the following comment to that post:

There are actually loads of details like that to take into consideration. That may be a nice level to deliver up. I provide the ideas above as normal inspiration however clearly there are questions like the one you carry up where a very powerful factor can be working in trustworthy good faith. I don?t know if greatest practices have emerged around things like that, however I’m positive that your job is clearly identified as a good game. Each boys and girls feel the affect of just a moment’s pleasure, for the rest of their lives.

The internet is a funny place.

Mobile coverage

A friend and regular Stubborn Mule reader drew my attention to an article in the Sydney Morning Herald this week about the Australian telco Telstra. Much of the recent commentary has focused on the implications of the national broadband network (NBN) for Telstra. While the NBN certainly gets a mention here too, for me the most striking paragraph deals with the extraordinary success Telstra has been having of late in the mobile phone market:

In the December half, the group added 420,000 bundled customers — customers on bundled deals tend to be “stickier” and stay with a telco longer than those who sign on for only one service — and it added 139,000 retail fixed broadband customers. Most importantly, it added 919,000 mobile phone customers: that’s the biggest mobile phone customer growth Telstra has produced for more [sic] a decade.

Gaining almost 1 million new customers in six months is quite an achievement in a country with a population of around 22 million. My own experience may shed some anecdotal light on Telstra’s success. I switched from Virgin mobile to Telstra late last year. The main reason was network quality. Virgin use the Optus network which I found extremely unreliable, even in central parts of Sydney. Sitting in a café in Glebe with no signal and seeing the person next to me with four bars on a Telstra phone had become too much. Customer service did not come into the decision: as far as I can tell, all the providers are equally atrocious on that score. So that just left price. When I first signed up with Virgin a couple of years earlier, Telstra may have had the superior network, but charged a hefty premium for it. But since then their prices have become far more competitive, which made the decision to switch very easy. I know a number of other people who have switched for exactly the same reason.

Even so, 1 million new customers is an impressive result for such a short period of time. This prompted my source to do some further research. According to a Wikipedia article about mobile phone penetration, in 2006 Australia’s population of 20.8 million owned 19 million mobile phones*. By 2007, that figure had grown to 21.3 million while the population was up to 21.2 million and so there was more than one phone for every man woman and child in the country. I have no doubt that the number of mobile phones has continued to grow faster than the population since then.

But despite over 100% mobile phone penetration, Australia is far from being the country most in love with mobile phones. The chart below uses the Wikipedia statistics to show the top 20 countries and the statistics are intriguing and not a little mysterious.

Top 20 Countries by Mobile Phone Penetration

Montenegro is clearly in the lead with almost two phones per capita. There is a bit of a drop down to Saudi Arabia with a penetration rate of 170%. On 151%, Hong Kong comes in third and leads a closely packed group all close to the 150% mark. Continuing down the list, penetration rates fall gradually down to Chile at 113% which means that Australia does not even make it into the top 20. In fact, even New Zealand ranks higher in 23rd place, while Australia is only in 31st place.

Of course, differences in timing of both the phone and population figures mean that the Wikipedia article will not be very accurate, but the overall picture remains impressive for someone like myself who is old enough to remember a time before mobile phones. And if anyone has any theories why Montenegro has so many mobile phones, please share your theory in the comments below!

* Unfortunately the Wikipedia article cites no source for the 19 million figure. Population statistics are sourced from the Australian Bureau of Statistics.

A gentle introduction to R

Whenever a post on this blog requires some data analysis and perhaps a chart or two, my tool of choice is the versatile statistical programming package R. Developed as an open-source implementation of an engine for the S programming language, R is therefore free. Since commercial mathematical packages can costs thousands of dollars, this alone makes R worth investigating. But what makes R particularly powerful is the large and growing array of specialised packages. For any statistical problem you come across, the chances are that someone has written a package that will make the problem much easier to get to grips with.

If it was not already clear, I am something of an R evangelist and I am not the only one. The growing membership of the Sydney Users of R Forum (SURF) suggests that we are getting some traction and there are a lot of people interested in learning more about R.

Sooner or later, every R beginner will come across An Introduction to R, which appears as the first link under Manuals on the R website. If you work your way through this introduction, you will get a good grounding in the essentials for using R. Unfortunately, it is very dry and it can be a challenge to get through. I certainly never managed to read it from start to finish in one sitting, but having used R for more than 10 years, I regularly return to read bits and pieces, so by now I have read and re-read it all many times. So, useful though this introduction is, it is not always a great place to start for R beginners.

There are many books available about R, including books focusing on the language itself, books on graphics in R, books on implementing particular statistical techniques in R and more than one introduction to R. A few weeks ago I was offered an electronic review copy of Statistical Analysis With R, a new beginner’s introduction to R by John M. Quick. Curious to see whether it could offer a good springboard into R, I decided to take up the offer.

At around 300 pages and covering a little less ground, it certainly takes a more leisurely pace than An Introduction to R. It also attempts a more engaging style by building a narrative around the premise that you have become a strategist for the Shu army in 3rd century China. The worked examples are all built around the challenge of looking at past battle statistics to determine the best strategy for a campaign against the rival Wei kingdom. Given how hard it can be to make an introduction to a statistical programming language exciting, it is certainly worth trying a novel approach. Still, some readers may find the Shu theme a little corny.

The book begins with instructions for downloading and installing R and goes on to explore the basics of importing and manipulating data, statistical exploration of the data (means, standard deviations and correlations), linear regression and finishes with a couple of chapters on producing and customising charts. This is a good selection of topics: mastery of these will provide beginners good grounding in the core capabilities of R. Readers with limited experience with statistics may be reassured that no assumptions are made about mathematical knowledge. The exploration of the battle data is used to provide a simple explanation of what linear regression is as well as the techniques available in R to perform the computations. While this approach certainly makes the book accessible to a broader audience, it is not without risks. Statistical tools are notorious for being abused by people who do not understand them properly. As a friend of mine likes to say, “drive-by regressions” can do a lot of damage!

Each chapter adopts the same structure: a brief introduction advancing the Shu story; a list of the topics covered in the chapter; a series of worked examples with sample commands to be entered into the R console followed by an explanatory “What just happened?” section and a “Pop quiz”; suggestions for further tasks for the readers to try; and finally a chapter summary. At times this approach feels a little repetitive (and the recurring heading “Have a go hero” for the suggested further tasks section may sound a little sarcastic to Australian readers at least), but it is thorough.

If I were to write my own introduction to R (one day perhaps?), I would do some things a little differently. I would try to explain a bit more about the semantics of the language, particularly the difference amongst the various data types (vectors, lists, data frames and so on). But perhaps that would just end up being as dry as An Introduction to R. Also, though I certainly agree with Quick that commenting your code is a very important discipline (even if no-one else ever reads it, you might have to read it again yourself!), I do think that he takes this principle too far in expecting readers to type all of the comments in the worked examples into the console!

Statistical Analysis With R is a very gentle introduction to R. If you have no prior experience of R, reading this book will certainly get you started. On the other hand, if you have already started experimenting with R, the pace may just be a little too slow.

NBN in more than 140 characters

migNow that Labor has scraped their way back into power, it looks very likely that the National Broadband Network will go ahead in some form or another. Debates on the merits of the scheme continue apace, not least on Twitter, conveniently labelled with the #nbn hashtag. One frequent twitter on this topic, @pfh007, is also a regular commenter here on the Stubborn Mule. It seems that his thoughts on “Fibre to the Home” (FTTH) can no longer be constrained to a mere 140 characters, so he has now written a guest post for the Stubborn Mule.

A friend asked me a few days ago whether I could state my position on the current NBN proposal in 140 characters or less.

Although 140 characters suits my attention span and typing speed, the FTTH NBN proposal requires a few more.

Please note I have no academic, technical or professional background in this area to give weight to my opinion. So take it for what it is – sideline commentary from my IT shed. But first an initial comment about the FTTH NBN debate.

Unlike many commentators, I do not feel that the debate has been sterile or shallow. Certainly, there has been some partisan barracking where views expressed seem to be simply based on what position a person’s political team is taking on the issue, and some commentators have let their passions get the better of their reason, but overall I have found a broad range of thoughtful and considered thinking on the issue in both the traditional and electronic media. I am confident that a full and frank debate about the FTTH NBN proposal will eventually result in a policy that will be in the interests of all Australians.

Some important throat clearing comments first up:

  • I believe that Australia needs better broadband access.
  • I agree that optical fibre is technically the superior technical solution to supplying fast high capacity broadband.

Some other important considerations:

The attempt in Australia to regulate a private monopoly of the fixed connection network was a dismal failure. It seems clear to me that the government must resume an important controlling role in the delivery of a fixed connection network to ensure that at least some regard is given to the public interest. Accordingly, it is important that the government buy back the farm (a.k.a the wholesale fixed connection network currently owned by Telstra).

Having bought back the farm, the government should immediately sell down its interest to 51%. The remaining 49% can be sold to private investors, ideally the retail suppliers who have, or should have, an interest in the provision of a high quality fixed connection network and thus actively contribute to ensuring that the fixed connection wholesale supplier is well run. One approach might be simply to leave a 49% interest with Telstra and let them sell down their share as they see fit.

The advantage of this approach is that the new wholesale fixed connection entity would immediately have a source of cashflow and the capacity to generate a commercial rate of return. Some of that cashflow could then be allocated to the improvement of the fixed connection network – more on that below. Additional investment could be raised by debt or capital investment by the shareholders. In short this entity would be making money from wholesaling access to the existing copper network.

The 51% government stake in the new wholesale organisation must remain in public hands as regulating private monopolies does not seem to be a strong point of our public administration.

While I am not entirely convinced that, given the choice, consumers over the next decade will continue to believe that a fixed connection for telephone/ internet is necessary, for reasons set out below I have assumed that every house will want and continue to require a fixed connection.

On the assumption that a fixed connection to every house remains desirable, it seems sensible that any new connections to new houses should be via an optical fibre. While I have no statistics to back me up, the cost of laying a new fibre connection as opposed to a new copper connection to a new house should be roughly similar. To the extent that optical fibre may be more expensive, the advantages of that technology would greatly exceed the difference in cost.

Households who currently have little or no access to a decent ADSL or HFC cable connection (the stuff used by Optus and Foxtel Pay TV) should be prioritised for improved connections. These connections could be initially fibre to the node (FTTN), to allow fast ADSL access, and eventually FTTH or if it is more cost effective to skip the interim FTTN step, FTTH immediately .

Fibre connections to public buildings or commercial premises should be given high priority as these users are much more likely to benefit from and be in a position to make practical use of the faster broad band connection that FTTH allows. Most of the applications for FTTH that I have read about seem most relevant to public or commercial buildings.

Households who currently have good quality ADSL or HFC connections would be given a much lower priority and may not be converted to FTTH for a long time or at least until demand clearly requires or the proposal outlined below is implemented. Assessing demand will be quite easy as, by that time, large numbers of new houses will have acccess to FTTH and word will have spread if it proves to be a compelling proposition for residential users. We will not need to speculate whether consumers will choose to improve their existing ADSL or HFC fixed connections to optical fibre.

Where sections of the existing copper network fail or prove to be more expensive to maintain than to replace they should be replaced with fibre.

Competition by private wireless networks should continue and be encouraged.

Will there be a continuing need for fixed connections to households?

Perhaps the greatest weakness of the current FTTH NBN proposal is the assumption by its proponents that a majority of households will wish to maintain a fixed connection (for telephone or internet) of any description to their home.

Increasingly many people, particularly young people, do not bother having a fixed phone connection at all. They have a mobile number and that is that.

This trend seems highly unlikely to reverse.

What does this mean for internet access via a fixed connection, arguably the only remaining persuasive reason for a fixed connection to many houses?

This year can be regarded as the year of the smart phone/smart appliance.

Although Apple iPhone had the field much to itself over the last few years, the rise of android, improvements to Nokia’s symbion and the impending arrival of Win 7 mobile seem likely to herald the storming of the mass market by smart phones.

Needless to say the market for iPads, tablets and e-readers will only further expand the demand for mobile internet access.

Although the limitations of wireless broadband are obvious to the old hands of fixed broadband (myself included) it is dangerous to assume that young people whose primary experience of the internet is framed by their smart phone gadget will see things the same way.

It may be that for most of their needs their smart phone will be perfectly fine and they will see no more need for a fixed broadband connection than they do for a fixed telephone connection.

Simply put – they may settlle for second best wireless connection because second best suits what they want from the internet.

They may wish for improved wireless broadband but it is not safe to assume that they will have a need for a fixed broadband connection simply because it is technically superior.

Mobility may trump speed and capacity.

At the present time, in the midst of explosive growth in consumer demand for mobile connections, the proponents of a FTTH NBN network are simply failing to articulate a persuasive case as to why the community should spend a large amount of money replacing the existing copper and HFC cable connections to the millions of households who currently have access to adequate broadband connections using those technologies.

To the extent that it is possible to gauge consumer interest in the FTTH NBN, it is clear that there will be insufficient consumer demand for its high speed fixed connections unless the consumer is denied the current fixed connection alternatives available to many of them – copper and HFC cable.

The most compelling argument in favour of a FTTH NBN

I have read much about the exciting ways the capacity and speed of FTTH broadband can be applied, but few of them are convincing as mainstream applications for residential users.

I appreciate that this may simply reflect the limits of my imagination and the imaginations of the current crop of futurists vibing the brave new world of FTTH, so I will keep an open mind that someone will come up with something in due course.

I believe there is only one application that makes a compelling case for a FTTH fixed connection network. Broadcast TV and video on demand including Pay TV and IP TV.

If radio tramission of all television was to cease when an area is fully supplied with FTTH and all free to air TV was supplied via the FTTH then many, if not all, households would demand a connection and a device that would allow them to feed the TV signal into their TV set.

Not only would this create a genuine need for FTTH but it would allow the considerable amount of valuable radio spectrum currently used by the analogue and digitial television broadcasts to be reused for other purposes including possibly 3G and 4G wireless.

There seems little justification for continuing to use valuable radio spectrum for the purpose of delivering SD and HD video programming which could be delivered simply and effectively by an optical fibre.

It is better that as much radio spectrum as possible is available for the provision of mobile internet access particularly as it is likely that mobile internet access will be favoured by many if not most consumers.

The auction of that spectrum to telcos and other wireless internet providers would go someway to defray the cost of the FTTH roll out, particularly those sections of the FTTH network where a universal service obligation may be the only reason for construction.

The availability and universal coverage of the FTTH would also allow multiple existing and new pay TV providers to use the cable as their main method of service delivery – especially to areas not currently supplied by existing technologies.


In short the proposal is as follows:

  • Have the government buy back a 51% interest in the wholesale fixed network – buy back the copper (this new wholesale fixed connection supplier would generate an immediate return from the existing copper fixed telephone and ADSL connections)
  • Fixed connections to new housing to be optical fibre
  • Existing houses with no access to HFC networks or ADSL to be provided with FTTN (or possibly FTTH)
  • Prioritise optical fibre connections to public buildings and commercial premises
  • No change to FTTH for existing houses with HFC or decent ADSL until it is clear that there is consumer demand to do so
  • All existing free to air TV to be supplied via the optical fibre to build community acceptance for non-broadcast supply of TV
  • As engineering and technical resources (including labour) allow progressively convert TV broadcast regions to FTTH and when connections are complete and operating turn off the broadcast TV signal
  • Auction the broadcast TV digital and analogue spectrum for alternate uses – say 3G and 4G wireless

The irony inherent in the proposal set out above is that while the FTTH connection could be used for ‘internet access’ as we currently understand it, the primary objective of the FTTH would be to facilitate the provision of increasing amounts of wireless internet access to mobile devices by removing TV (analogue and digital) from the radio spectrum.

Furthermore, it also suggests that the proponents of a FTTH NBN might be better served by promoting the capacity of the FTTH to deliver TV, pay TV and other forms of video entertainment that the consumers value highly as this would allow improved wireless connections to deliver the lion’s share of the internet access that most consumers are likely to want in the future.

For remote houses that cannot be connected with FTTH – satellite delivery of free to air TV and Pay TV should be available.

How old is the Mule?

According to one automated blog analyser, I am rather older than I thought I was: is probably written by a male somewhere between 66-100 years old. The writing style is academic and upset most of the time

The gender is correct and academic writing style I can accept, but I am not so sure about being upset most of the time. Generally I am quite happy while writing the blog!

Protovis now working in Chrome and Safari

Thanks to everyone who responded to my experimental Protovis post*, whether in the survey, via twitter or in comments on the post. It quickly became clear that my trick for including the code to generate the chart completely failed to work in Chrome and Safari browsers. I still do not fully understand why that is, but I have now worked out a completely different approach to the problem which (fingers crossed) seems to work in more browsers, although I still cannot vouch for all versions of Internet Explorer.

So here is the chart one more time. I hope it now works for (almost) everyone!

[pvis src=”” img=”/blog/wp-content/PV-CDO-circles.png” height=”125px”]CDO deals: total and recycled[/pvis]
I will also be updating the howto post very shortly to explain my new technique.

UPDATE: at the moment, this trick is not working on mobile devices. It should now be working on mobile devices except for Android. The only remaining problem is IE, but I think that will not be possible. I will instead try to make it fail more gracefully on IE.

* Protovis is a javascript data visualisation library being developed at Stanford, which allows the creation of interactive charts on web pages.

Getting Protovis working on WordPress

When I started experimenting with Protovis*, I quickly found that getting it to work in a WordPress blog was rather fiddly. With a lot of help from Google (and this page in particular), I managed to piece together what needed to be done, but since I did not find any explanations specifically focused on Protovis in WordPress, I thought it may be useful for others attempting the same thing if I summarised the steps involved. Most readers will not have the slightest interest in this, so I will not expect many of you to keep reading!

First of all, if you are hosting your blog on, give up now! These instructions will only work if you have a self-hosted installation of WordPress.

1. Download Protovis and unzip it on your server it a convenient location. I put it in a folder called “protovis”, accessible from the root of the webserver.

2. Ensure your headers include a pointer to the Protovis script. How exactly you do this, depends on your theme, but since I am using Thesis, it’s quite straightforward: under Site Options > Additional Scripts, I added the following code.

<link rel="shortcut icon" type="image/x-icon" href="/favicon.ico">
 <script type="text/javascript" src="/protovis/protovis-r3.2.js"></script>

3. Wrap your Protovis code up in a function and save it in a .js file on the server. For example, here is the code I used to produce the chart in the last post. You will see that I wrapped everything up in a function called “cdodraw”. I saved the file in the folder /script/pv.

4. Edit your post in HTML mode and use the following code to load and call your function.

<script src="/scripts/pv/cdodraw.js" type="text/javascript"></script>
<script type="text/javascript+protovis"><!--

You should replace “/scripts/pv/cdodraw.js” with the location of your own Protovis chart code and replace “cdodraw()”. With the name of your own function. Note that the first script command has type “text/javascript” and the second “text/javascript+protovis”. This is important!

Part of the reason for the difficulty is that WordPress has a tendency to mash up the text you enter, which is fine most of the time, but not when you are trying to write Javascript. An alternative may be to try the Text Control plugin, which allows finer control over WordPress’s mashing of your text. I have not tried the plugin myself, so I cannot be sure how well it works.

Good luck, and let me know how you go! If you have any suggestions on how to do this a better way, please let me know. Better still, you could write a WordPress plugin to make it all much easier.

UPDATE: it appears that this function-wrapping trick does not work for Google Chrome or Safari. I’m looking into it!

FURTHER UPDATE: I could not work out why the approach described here does not work for Chrome or Safari, so instead I got it working by creating a custom shortcode that slurps in a javascript file and includes it in the post. I am in the process of wrapping this up in a plugin to save others the trouble of working out how to do it. For those who cannot wait, here is the code I used:

function sProtovis($atts, $content = null) {
 extract(shortcode_atts(array('src' => '#'), $atts));
 return '<script type="text/javascript+protovis">'."\n".file_get_contents($src).'</script><noscript>Scripts disabled -- cannot display chart!</noscript>'.'<p align="center"><strong>'.do_shortcode($content).'</strong></p>';
add_shortcode('protovis', 'sProtovis');

It still relies on the Protovis code already being added into the header (as described above). In the plugin, this will no longer be necessary.

PLUGIN: pv-loader is now available on github.

* Protovis is a javascript data visualisation library being developed at Stanford, which allows the creation of interactive charts on web pages.

Experimenting with Protovis

A couple of weeks ago I gave a talk on using graphics in R. During the question session, someone asked whether I had tried using Protovis, a javascript data visualisation library being developed at Stanford. It was an easy question to answer: no!

However, a bit of subsequent investigation revealed that Protovis has been developed very much in the spirit of Leland Wilkinson’s book The Grammar of Graphics, which I am currently reading, so I have decided to experiment with it here on the blog.

The charts I generate with R are all static images, while a tool like Protovis allows for user interaction which opens up some interesting possibilities. Compared to R, which I have been using for around 10 years, Protovis presents a double challenge: not only do I have to come to grips with Protovis itself, but I will also have to learn some basic Javascript programming. So, I expect it to be a slow journey.

As a tentative first step, I have reproduced the CDO chart from a recent post ranting about bubble charts. At first glance, it is essentially identical to the chart I produced using R. However, if you hover your mouse over the points on the chart, you should see the figures appear! It is by no means perfect (for example, it would probably look better if single points appeared, rather than every point on the chart and it could do with a legend), but it’s a start and I will persevere.

[pvis src=”” img=”” height=”125px”]CDO deals: total and recycled[/pvis]

Producing scripts using a Javascript library does have its drawbacks. For a start, it means the chart will only be visible when scripts can be run, so if you are reading this in an email or an RSS news reader, you will probably not see very much and will have to visit the page on the blog to see it. Even then, some of you may use script-blockers such as NoScript which will also break the chart (mind you, you can trust the Mule, so you could always whitelist this site!). Finally, I believe that some older browsers (such as IE6) will not support Protovis. It would be useful to see how many people can or cannot see the chart, so please let me know using this poll whether you can see the chart.


Getting Protovis to work on the blog was a little fiddly, so for anyone interested, I have also written up a quick guide to using Protovis on a WordPress blog.

UPDATE: Reports in so far indicate that the chart is not working in Google Chrome or on mobile devices. More work to do it would seem!

The Mule goes SURFing

A month ago I posted about “SURF”, the newly-established Sydney R user forum (R being an excellent open-source statistics tool). Shortly after publishing that post, I attended the inaugural forum meeting.

While we waited for attendees to arrive, a few people introduced themselves, explaining why they were interested in R and how much experience they had with the system. I was surprised at the diversity of backgrounds represented: there was someone from the department of immigration, a few from various areas within the health-care industry, a group from the Australian Copyright Council (I think I’ve got that right—it was certainly something to do with copyright), a few from finance, some academics and even someone from the office of state revenue.

Of the 30 or so people who came to the meeting, many classed themselves as beginners when it came to R (although most had experience with other systems, such as SAS). So if there’s anyone out there who was toying with the idea of signing up but hesitated out of concern that they know nothing about R, do not fear. You will not be alone.

The forum organizer, Eugene Dubossarsky, proceeded to give an overview of the recent growth in R’s popularity and also gave a live demo of how quickly and easily you can get R installed and running. Since there were so many beginners, Eugene suggested that a few of the more experienced users could act as mentors to those interested in learning more about R. As someone who has used R for over 10 years, I volunteered my services. So feel free to ask me any and all of your R questions!

As well as being a volunteer mentor, I will have the pleasure of being the presenter at the next forum meeting on the 18th of August. Regular readers of the Stubborn Mule will not be surprised to learn that the topic I have chosen is The Power of Graphics in R. Here’s the overview of what I will be talking about:

In addition to its statistical computing prowess, R is one of the most sophisticated and flexible tools around for visualizing quantitative data. It can produce a wide variety of chart types, including scatter plots, box plots, dot plots, mosaic plots, 3D charts and more. Tweaking chart settings and adding customized annotations is a breeze and the charts can readily be output to a range of formats including images (jpeg or png), PDF and metafile formats.

Topics covered in this talk include:

  • Getting started with graphing in R
  • The basic charting types available
  • Customising charts (labels, axes, colour, annotations and more)
  • Managing different output formats
  • A look at the more advanced charting packages: lattice and ggplot2

Anyone who ever has a need to visualize their data, whether simply for exploration or for producing slick graphics for reports and presentations can benefit from learning to use R’s graphics features. The material presented here will get you well on your way. If you have ever been frustrated when trying to get charts in Excel to behave themselves, you will never look back once you switch to R.

For those of you in Sydney who are interested in a glimpse of how I use R to produce the charts you see here on the blog, feel free to come along. I hope to see you there!