Sampling Strava again

I thought I’d repeat the experiment conducted by Mark Slavonia last year to see how the Strava usage numbers stack up now.
First I needed to know the number of signed up users of Strava. This is pretty straightforward, head off to https://www.strava.com/athletes/6161562 and keep increasing the number at the end until Strava says it can’t find a user. Last March there were 8.2 million users, now there are about 14.4 million, not a bad increase for just over a year.
Next I wanted to capture the active users and the premium users. Since I’m a techy, I can automate this process using the Strava API and a .NET wrapper around it. So I decided to sample 1 in every 10,000 users, giving me about 1,440 sample users which should give the results a reasonable accuracy.
After pulling down that data, the first thing I noticed was that 47 of my requests had returned ‘Not Found’ errors. In fact, most of these were grouped together, suggesting Strava decided to restart their numbering with larger IDs at some point. So the total number of users is probably just shy of 14 million.

Premium Users

Of the 1.393 users I had left, 28 were Premium users, so approximately 2% of all users. This figure is pretty close to last year’s figure so I’m happy to believe it. That equates to 280,000 premium users or $16.6 million in revenue for Strava.
As an aside, I’m a Premium member, but not because Strava offers particularly compelling features for Premium users, but mainly to show my support for a website that is exceedingly useful and fun. I suspect Strava could differentiate between free and Premium a lot more to increase the percentage of Premium users. Take a look at all the functionality available at veloviewer.com.

Active Users

The Strava API doesn’t let me get activity data for other users, so I’m not able to find out how active users are directly. But it does provide an Updated field, which I’m hoping gets updated when a user uploads an activity (the Strava API docs are a little vague on this point). Using last year’s definition of an active user being someone who has done something in the last 24 days, how many active users are there? I found 181 users where that Updated field was in the last 24 days. That’s about 13%, or 1.8 million active users. The percentage is again fairly close to last year’s figure so I’m happy to go with it.

Gender

I found 806 men and 270 women and 317 blanks. Ignoring the blanks, that almost exactly a 75% / 25% split between men and women.

By Country

I think my sample is too small to draw accurate conclusions from the home countries of Strava users, but lets play with the numbers anyway. 463 had blank entries for the country which leaves 930 users with a country specified. I’ve removed countries with less than 5 users in my sample and then adjusted for population. Below I’ve highlighted the countries where more than 2% of the population have signed up for Strava. It seems like there is massive potential to increase usage in many countries, although that may depend on whether there is a culture of recreational running and riding in these countries (China and India being the obvious biggest potential markets). And little old blighty, the UK, is top of the pile. Go UK!

Country	Population	Sampled users	Approximate Strava users	% of population
Australia	24,309,330	35	527,000	2.2
Austria	8,569,633	5	75,000	0.9
Belgium	11,371,928	6	90,000	0.8
Brazil	209,567,920	74	1,114,000	0.5
Canada	36,286,378	25	376,000	1.0
Chile	18,131,850	6	90,000	0.5
Colombia	48,654,392	9	135,000	0.3
Denmark	5,690,750	5	75,000	1.3
France	64,668,129	35	527,000	0.8
Germany	80,682,351	18	271,000	0.3
India	1,326,801,576	5	75,000	0.0
Ireland	4,713,993	9	135,000	2.9
Italy	59,801,004	37	557,000	0.9
Japan	126,323,715	9	135,000	0.1
Mexico	128,632,004	6	90,000	0.0
Netherlands	16,979,729	32	482,000	2.8
New Zealand	4,565,185	9	135,000	3.0
Philippines	102,250,133	8	120,000	0.1
Poland	38,593,161	5	75,000	0.2
Portugal	10,304,434	16	241,000	2.3
Romania	19,372,734	6	90,000	0.5
Russia	143,439,832	12	181,000	0.1
South Africa	54,978,907	16	241,000	0.4
South Korea	50,503,933	14	211,000	0.4
Spain	46,064,604	46	692,000	1.5
Switzerland	8,379,477	7	105,000	1.3
Taiwan	23,395,600	14	211,000	0.9
Ukraine	44,624,373	6	90,000	0.2
UK	65,111,143	153	2,303,000	3.5
US	324,118,787	233	3,508,000	1.1

Strava segments by year

I thought I’d do a little analysis of the data I’m slowly collecting on my Strava segment explorer. Every segment has a numeric ID and these started at 1* and each new segment gets an ID of one greater than the most recent segment. So it’s quite easy to figure out how many segments are getting created over time.
So since I don’t have a huge dataset to analyse, lets see how many segments had been created at the end of every year.

So what’s this tell us? It shows the total number of segments created at the end of every year and it looks like since 2011, the number of segments created every year has remained fairly constant. I guess the interesting question would be whether creation of segments can be used as some kind of proxy for usage of Strava since Strava keep this information confidential? I think the answer to that is probably no. A new user in an area already choc full of segments probably isn’t going to feel the need to create more, although they may create a few personal ones (home to work etc). Long term users probably already have all the segments they need. A better approach would be to repeat this study from last year.
But I guess it does show Strava is still being actively used by its users, beyond that it’s hard to say anything definitive.
*Not entirely true, the lowest ID I’ve found is 96, but I imagine the ID of the first segment ever created was 1.

UK property sales data for February 2016

I've uploaded the latest Land Registry data to my site. Prices continue on their merry upwards trajectory

UK postcodes with altitude data

After much faffing around, I have finally added altitude data to my postcode data. Altitudes should be included with all the various CSV downloads. Hopefully these are reasonably accurate, but let me know if you find anything obviously wrong.

UK house price data January 2016

I’ve uploaded the latest Land Registry data to my site. The source file is a lot bigger than usual and seems to contain quite a lot of old sales.

Prices are rising even faster and the number of sales is on the increase.

February 2016 UK postcode data

I’ve uploaded the latest ONS postcode data to my website. I have run my usual sanity checks and it all seems OK but let me know if you spot any problems

Cycling speed variations with time of year

I’ve always assumed summer is the time of year when I will cycle the fastest. My ride data seems to back this up, with my average summer riding speed higher than my winter speed, but there are so many variables it is difficult to be definitive about it. For instance, during the summer I’m more likely to head out of the city and ride on some roads without too much traffic and fewer red lights, so I manage to maintain a higher average speed (although another variable to throw in is I tend to go up bigger hills where I’m slower!). Also I ride more during the summer so my overall fitness is probably higher. So maybe the difference in speed is not weather or temperature related.

But I was still surprised to read someone suggesting they go faster in the winter. The only time this happens to me is when I’m out during a windy winter day and catch a nice tailwind.

But I thought I’d check the Strava data from my site. Which months have the most KOMs? Checking that removes at least one variable, different roads. First I had to update my site to store the KOM date for each segment then I had to grab some data. I chose segments in the UK, removing those that were less than 0.5km (too easily messed up with dubious GPS data) and removing segments with less than 100 riders (not competitive enough) and this is what I got.



This is a fairly small sample but it certainly suggests the summer months are the best time to grab a KOM, which also suggests the summer is the fastest time of the year for cycling. But then a thought crossed my mind, people tend to cycle more during the summer months, so perhaps it’s unsurprising that most KOMs are achieved then. So my conclusion is that I still have no idea and more research is required. And there are too many variables…
For my own recollection, this is the SQL I used to grab the data
SELECT MONTH(KOMDate), COUNT(*) FROM segments
WHERE Country='United Kingdom' AND
Distance>500 and
TriesCount>100 and
KOMDate IS NOT NULL
GROUP BY MONTH(KOMDate)
ORDER BY MONTH(KOMDate)

UK Property Sales December 2015

I've uploaded the latest Land Registry house sale data to my website. House prices and sales volumes continue on their upward march

UK house prices November 2015

You can now view and download UK house price data for November 2015 from my website. Not much to report, prices continue on their ever upward trajectory, transactions appear to be creeping upwards

UK house price data for October 2015

I’ve uploaded the latest Land Registry house sale data for England and Wales to my website.

Postcode data for November 2015

I’ve uploaded the latest ONS postcode data for November 2015 to my website, all 2,554,806 of them. I’ve run my usual checks but let me know if you spot anything that looks incorrect.

Fixing Strava elevation data

For some reason, Strava actually trust the data that comes from their users. More specifically they use the elevation data from the user’s ride when the user creates a segment. From a technical point of view, this is definitely the easiest thing to do, but unfortunately GPS devices do occasionally lose their mind, so the data can be a mess. This can lead to garbage segment data, like this. A glance at the elevation profile makes it obvious that something is amiss. This dodgy data then means any derived data is also dubious, such as the climb category and the VAM numbers. The KOM rider on this particular segment has a VAM of 9,992 which is over 5 times what a drugged up Lance Armstrong could achieve. Even my average VAM on category 4 climbs is over 1,000 which suggests I could make a good fist of keeping up with a bunch of professional cyclists. Which I couldn’t. Ever.
In an ideal world, Strava would fix up these dodgy segments in some way. One fix would be to average out all the elevation data from every rider who has ridden a segment. Alternatively, they could use the elevation data from one of the mapping services. Finally, they could make it easier to report bad data.
So whilst we wait for Strava to fix this issue, I thought I’d have a play with the second option. My Strava segment search tool now has the ability to view segments as well as view them on Strava. This is what the example segment looks like. It use Google Maps to calculate the elevation of the segment and adds that to the elevation profile, along with calculated statistics.

UK stations data

As a prelude to some other work I might one day get round to, I’ve uploaded a list of UK train stations to my website. It comes in CSV and KML flavours, with the KML highlighting the busiest stations (mostly in the South East, as if you need to ask).

UK property sale data for September 2015

It’s the end of the month so it’s time to upload the latest Land Registry property data to my website. The data crunching is still in progress but I’m off on holiday for a few days so can’t wait for it to complete before posting here (calculating all the various averages can take quite some time). Predictably enough, the data shows house prices continuing their upward march.

One sale this month caught my eye. Flat 4, 19 Terrapin Road was the first flat we bought, back in 1999. It’s just changed hands again, for a cool £530,000. So in 16 years, the price has increased over fivefold… Just one example of the insanity of the London housing market.

UK house prices August 2015

I’ve uploaded the latest house sale data from the Land Registry to my website. Prices seems to be ticking up at an increasing rate, numbers of sales are not changing much. One would imagine without an increase in volumes, prices can’t remain at their current high level. but I could have said the same thing for the past 7 years…

UK Property Sales July 2015

I have uploaded the latest Land Registry house price data for Jul 2015 to my site. Prices continue to rise moderately and sales continue to be at a low level

August 2015 UK postcode data

I’ve uploaded the latest UK postcode data to my website. It now contains 2,551,959 postcodes, including live and terminated postcodes. I’ve run sanity checks on the data and all appears well but let me know if you spot any problems.

How to top a Strava segment leaderboard

Strava is all about the segments and bragging rights are gained by being top of the leaderboard for a segment. But for those of us living in areas with many other cyclists, we are very unlikely to be fast enough to top most of the local segments, even if we get pushed along by a massive tailwind. Here’s an example near me, with nearly 50,000 riders attempting it over half a million times. The leaderboard contains a number of professional cyclists, since a number of races have passed through, so I’m never going to get anywhere near the top (since you asked, I’m at about 10,000 currently).
But we all want our own KOM/QOM, so what to do?

Find an obscure segment

Head over to my Strava segment search tool and zoom in and pan around a bit. You should see quite a few more segments than you’ll find with Strava’s own search. They’ll generally be less popular segments and hence more likely to have beatable times. 

Create your own obscure segment

I have a couple of KOMs for my rides to and from work. These are fairly meaningless KOMs since I’m the only person to ride one of the segments and the other one has only been ridden by one other rider. But if that’s enough to make you feel you’ve made it as a rider, then go ahead and create your own segment. For this to work, you need to decrease the chance of anyone else riding your segment, so stick to obscure roads, make the segment fairly long and choose a route that nobody would ever normally follow. This is a brilliant example, one day I’ll get round to riding it to see if I can top the leaderboard

Keep riding

A while back I headed out on a ride, going down some roads I haven’t explored before. On getting home I discovered I’d topped a leaderboard without even trying. Admittedly only 10 other people have ridden the segment but it still counts!

Cheat

There are websites that will take the output from your bike computer and shift it around so it appears you went faster than you did. No, really. It’s obvious chasing after Strava KOMs is a fairly pointless activity, but cheating to do it has to be the most ridiculous thing ever.
But what about inadvertently cheating? Whilst on a ride, my GPS went a bit haywire and for a few minutes I was at the top of a leaderboard. I guess the algorithms at Strava spotted the mistake (or the former holder of the KOM) and I was demoted pretty quickly. But what about this one? Everybody on the first page of that leaderboard is averaging over 78mph, which is very impressive for a hilly segment round Richmond Park. But if you look at the actual rides for those amazing times, none of them bear any relation to the actual segment, they are just in the same general area. Figure out how that bug works and you could be topping lots of leaderboards.

UK property sales for June 2015

I've uploaded the latest Land Registry property sales data to my site. Not much to report, house prices continue to slowly rise, the number of sales are still fairly low.

Strava segment explorer

I’ve added a new page to my website that gives a new look at Strava segments. I’m not too keen on the segment explorer on the Strava site. It doesn’t let me zoom in fully so I can’t find obscure segments that a slow coach like me might have a chance of gaining a KOM. It also only ever displays 10 segments at a time so I can’t get a good feel of what’s around.
My explorer fixes these issues. I have a load of ideas on how to improve it, so let me know if you find it useful and what you’d like to see.

UK property sales May 2015

I’ve uploaded the latest Land Registry house price data to my site. Prices are still slowly ticking up but it seems the mini-boom in sales of 2013 and 2014 is over. 

UK postcode data for May 2015

I have uploaded the latest ONS postcode data to my website. This means all the latest postcodes in England, Wales and Scotland are now available. Northern Ireland continues to go its own way with its licensing so I am unable to update the postcodes I have from 2008. If you’d like to see up to date Northern Irish postcodes, I suggest contacting NISRA and ask them to relax their licensing to be in line with the rest of the UK.

UK house prices April 2015

I’ve just uploaded the latest Land Registry data for April 2015 to my website. Nothing of note to report, prices continue to rise at a slow pace.

Retrieving the most popular pages using Google Analytics API again…

I occasionally run a little app I wrote 4 years ago to grab the most popular pages on my website via Google Analytics and update the database so the website can display a top 10 list of those pages. I tried to run it this morning and it fell over in a heap. It seems that Google no longer supports the API I was using. Ho hum, shit happens, software does rust…

So time to drag out my old code. Except I couldn’t find it. So time to look at Google’s latest and greatest API and rebuild it from scratch. Here’s what’s required and a small code sample.

First download the Google API .NET libraries. There seem to be a whole host of Google API libraries in nuget, but for Google Analytics the following should get what you need and all the dependencies.

Install-Package Google.Apis.Analytics.v3

Then you’ll need to create a service account in the Google Developers Console. After creating this service account, create a P12 key for it and save it somewhere on your computer. Then add the service account email address to the Google Analytics account you want to access.

Next fire up Visual Studio and create a console application and add the following code

using Google.Apis.Analytics.v3;
using Google.Apis.Analytics.v3.Data;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using System;
using System.Security.Cryptography.X509Certificates;

namespace UpdateTop10
{
  class Program
  {
    [STAThread]
    static void Main(string[] args)
    {
      try
      {
        Read();
      }
      catch (Exception ex)
      {
        Console.WriteLine("ERROR: " + ex.Message);
      }
      Console.WriteLine("Press any key to continue...");
      Console.ReadKey();
    }

    private static void Read()
    {
      String serviceAccountEmail = "<the service account email address>";

      var certificate = new X509Certificate2(@"<the location of your P12 key file>",

        "notasecret", X509KeyStorageFlags.Exportable);

      ServiceAccountCredential credential = new ServiceAccountCredential(
         new ServiceAccountCredential.Initializer(serviceAccountEmail)
         {
           Scopes = new[] { AnalyticsService.Scope.AnalyticsReadonly }
         }.FromCertificate(certificate));

      // Create the service.
      var service = new AnalyticsService(new BaseClientService.Initializer()
      {
        HttpClientInitializer = credential,
        ApplicationName = "<your application name in Developer Console>"

      });

      // Run the request.
      DataResource.GaResource.GetRequest req = service.Data.Ga.Get("ga:<the ID of the analytics view found under Admin/View Settings>", DateTime.Now.AddMonths(-1).ToString("yyyy-MM-dd"),

        DateTime.Now.ToString("yyyy-MM-dd"), "ga:visits");
      req.Dimensions = "ga:pagePath";
      req.Sort = "-ga:visits";
      GaData data = req.Execute();

      for (int i=0; i<20; i++)

      {

        Console.WriteLine(data.Rows[i][0] + ": " + data.Rows[i][1]);
      }
    }
  }
}

Fill in the bits between angled brackets with your details and give it a go. The top 20 visited pages from the last month should appear in your output.


Overall it wasn’t too painful, Some of the examples on the web seem to be written for older versions of the API which can cause some confusion and Google have such a huge number of APIs out there, finding the right one can be tricky, but once those hurdles are overcome, it’s reasonably straightforward.

Update - Windows Live Writer currently doesn't work with Blogger accounts, I'm guessing this is the same issue that I was having with my old little app. Hopefully Google told everyone they were turning off ClientLogin support, but it appears Microsoft didn't get the memo... And hopefully it gets fixed soon, because the Blogger editor is effing terrible

UK constituency and administrative area KML

A strange thing happened last week, visits to my site were affected by real world events. That’s the first time that has happened. The cause was the UK election and the pages affected by it were the pages devoted to UK electoral constituencies and in particular the constituency of South Thanet. After having a look at those pages, I came to the conclusion that any visitors may have been quite disappointed with the data available on those pages. So I’ve spent a bit of time improving them. They now include the area polygons of each constituency and also provide an estimate of the population and number of households in each constituency.

Whilst i was at it, I also added area polygons for administrative districts and wards. Enjoy!

No trouble with counties

I wrote recently about the trouble I’ve had figuring out what to do about counties in the postcode data on my site. Thanks to a very helpful comment on that post, I finally figured what I hope is the correct course of action. Previously I only showed county information for postcodes that were located in a county council. The suggestion was to map postcodes to ceremonial counties, which I wasn’t really aware of before. But a quick look at Wikipedia suggested they was a pretty simple mapping between them and administrative areas, with the exception of a little complexity in Stockton-on-Tees. So that’s what I’ve done. You can now download postcode data for each English county here. Hopefully this meets all your county needs!  

Distance to sea, house price improvements

I made a few improvements to the website over the Bank Holiday weekend. Ever had a burning desire to know the distance from a postcode to the sea? Well now you can find out.

I’ve also updated the way individual house prices are listed so that all sales for a particular property are grouped together (example)

UK house price data March 2015

I’ve uploaded the latest Land Registry house price data for March 2015 to my site. Prices continue to chug along at 4-5%, as they have been doing for the last 12 months. The CSV download data now includes a yearly summary and I’ve included charts for this annual data at the postcode district level (monthly data is too volatile to show anything meaningful in such small areas)

The trouble with counties

I include some county information with my UK postcode download data, but I get quite a few questions regarding it. The most common question is why don’t all the postcodes have an associated county. The answer is that county information is only shown for postcodes that are located in an administrative county council. So LA1 postcodes are listed as part of Lancashire but BB1 postcodes aren’t, even though most people would consider Blackburn to be in Lancashire. This page gives you an idea of how this works. Select ‘Counties’ in the dropdown and see all the gaps.

The second question that generally follows is whether I could include county information for each postcode. This is where things get tricky. Have a read of this Wikipedia page on the subject of counties. In short, there are the administrative county councils in use today, there are historical counties whose boundaries have changed many times and there are postal counties that used to be supplied by the Royal Mail.

So if I wanted to add county information for every postcode, my first decision would be which of these to use. The Royal Mail seem pretty keen to get rid of postal counties and the information is not provided with the freely available postcode data, so that’s not an option.

So another option would be to use historical counties. Leaving aside the fact these boundaries changed many times, I’m not sure using them would satisfy most users of my download data anyway. Taking an example from the referenced Wikipedia page, how many people would consider Brixton to be in Surrey?

And the final option would be to fill the county data from the local authority. So Brixton would now be in London, but BB1 would now be in ‘Blackburn with Darwen’. Now in this case it’s obvious that any postcodes in the ‘Blackburn with Darwen’ area should show Lancashire as the county so I could possibly map all these authorities to sensible counties, with some work. But even then, would this provide people with what they want? Kingston would be in London, although some people would expect it to be in Surrey, since Surrey county council is based there (and use Surrey in their address).

So in conclusion, counties are blooming tricky and I suspect no one size would fit all, hence the incomplete set of data on my site. If anyone has an opinion on whether there is a good approach to this, let me know.

Cycling halfway round the world

In July 2012 I started to use Endomondo to track my bike rides. Since then some things have changed in my cycling, I’ve moved from a mountain bike to a road bike, I’ve tried cycling 100 miles in one day (only to be thwarted by the weather)and I’ve started using Strava, but I’ve continued to use Endomondo. And today I reached the milestone of getting halfway round the world.

Last year I covered almost 6,000 miles. If I can continue at that level, then in a just over a couple of years I will have completed my virtual trip round the world. If you want to encourage me, then you can sponsor me in this year’s Ride London 100…

Loading Google Maps asynchronously

Google’s PageSpeed keeps telling me I should load scripts asynchronously to improve the performance of my website. Now in an ideal world I’d use something like RequireJS to implement this for all my scripts, but frankly that seems like a bit of a big task and more than likely I’d stuff it up and break large chunks of my web site. So I thought I’d start small and just load up Google Maps asynchronously. Google provide an example of how to do this, but I wanted to encapsulate that in a simple reusable function with a callback function parameter to run after the library had loaded. This is what I came up with in TypeScript.

function loadGoogleMaps(libraries: string, callback: () => void) {

  window["initGM"] = () => {
    callback();
  };

  var script = document.createElement("script");
  script.type = "text/javascript";
  var url: string = "http://maps.google.com/maps/api/js?callback=initGM";
  if (libraries != null && libraries !== "") {
    url += "&libraries=" + libraries;
  }
  script.src = url;
  document.body.appendChild(script);
}

UK house price data February 2015

I’ve uploaded the latest Land Registry data to my site. Prices continue on their seemingly never ending upward march.

A cross browser XML parser

A post from three years ago detailing how to implement selectSingleNode for XML documents in a cross-browser friendly manner is still getting a good number of hits. Which I guess shows that developers still need to manipulate XML in browsers, even with the increasing popularity of JSON. When we started to rewrite our desktop app on the web, JSON seemed like the obvious choice, but we use XPath in a big way and we wanted our web app to be compatible with our desktop app, so we stuck with XML, which meant having to deal with the different ways XML is supported in different browsers. So we now have a reasonably well featured cross browser XML parser, the source of which you’ll find below.

A couple of things to note, this probably works in IE8 and below but I’ve never tested it since our app needs at least IE9. Also, the code is TypeScript rather than Javascript, since TypeScript is slightly less insane…

// stop TypeScript complaining about stuff we don't have definitions for
interface Window {
  DOMParser;
}
declare var XPathResult;

class XmlWrapper {
  private xmlDoc: any;
  constructor(xml: string) {
    try {
      // try Internet Explorer first. Although later versions have DOMParser, they don't implement evaluate
      this.xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
      this.xmlDoc.async = false;
      this.xmlDoc.loadXML(xml);
      this.xmlDoc.setProperty("SelectionLanguage", "XPath");
    } catch (ex) {
      if (window.DOMParser) {
        var parser = new DOMParser();
        this.xmlDoc = parser.parseFromString(xml, "text/xml");
      } else {
        throw new Error("Can't find an XML parser!");
      }
    }
  }

  public selectSingleElement(xmlNode, elementPath: string): Element {
    return <Element>this.selectSingleNode(xmlNode, elementPath);
  }

  public selectSingleNode(xmlNode, elementPath: string): Node {
    if (xmlNode == null) {
      xmlNode = this.xmlDoc;
    }

    if (this.xmlDoc.evaluate) {
      var doc = xmlNode.ownerDocument;
      if (doc == null) {
        doc = xmlNode;
      }
      var nodes = doc.evaluate(elementPath, xmlNode, null, XPathResult.ANY_TYPE, null);
      var results = nodes.iterateNext();
      return results;
    } else {
      return xmlNode.selectSingleNode(elementPath);
    }
  }

  public selectElements(xmlNode, elementPath: string): Element[] {
    return <Element[]>this.selectNodes(xmlNode, elementPath);
  }

  public selectNodes(xmlNode, elementPath: string): Node[] {
    if (xmlNode == null) {
      xmlNode = this.xmlDoc;
    }

    if (this.xmlDoc.evaluate) {
      var doc = xmlNode.ownerDocument;
      if (doc == null) {
        doc = xmlNode;
      }

      var resultsArray = [];
      var results = doc.evaluate(elementPath, xmlNode, null, XPathResult.ANY_TYPE, null);
      var thisElement = results.iterateNext();
      while (thisElement) {
        resultsArray.push(thisElement);
        thisElement = results.iterateNext();
      }

      return resultsArray;
    } else {
      return xmlNode.selectNodes(elementPath);
    }
  }

  get documentElement(): Element {
    return <Element>(this.xmlDoc.documentElement);
  }

  public xml(): string {
    // for IE
    if (this.xmlDoc.documentElement.xml) {
      return this.xmlDoc.documentElement.xml;
    }

    // Chrome, FireFox
    if (this.xmlDoc.documentElement.outerHTML) {
      return this.xmlDoc.documentElement.outerHTML;
    }

    // Safari
    return (new XMLSerializer()).serializeToString(this.xmlDoc.documentElement);
  }

  public static getNodeText(node: Node): string {
    if (node == null) {
      return "";
    }

    var value: string = node.text;
    if (node.textContent) {
      value = node.textContent;
    }

    return value;
  }

  public static setNodeText(node: Node, value: string): void {
    if (node == null) {
      return;
    }

    if (node.text !== undefined) {
      node.text = value;
    }

    if (node.textContent !== undefined) {
      node.textContent = value;
    }
  }
} 

Google Earth Pro is kind of free

I was excited when Google announced Google Earth Pro was going to become free. A lot of geographical data comes in Shape files, but these aren’t usable in any free applications I know of and can’t really be used on the web without converting to something like KML first. But Google Earth Pro can load up Shape files and convert them to KML/KMZ.

Downloading isn’t a problem but getting hold of a key doesn’t seem to work as far as I can tell. Following the link to grab a free key just keeps redirecting to the download page. So I gave up in the end and grabbed an illicit key instead. Not sure of the legality of that, but if it’s meant to be free and I still need a key and Google won’t give me one, what choice did I have? Anyway a search for “google earth pro serial key or number” gave me a link to a site that produced a key I could use.

UK house price data January 2015

I have uploaded the latest Land Registry house price data to my site. Prices continue their gradual ascent.

The BBC reports the blindingly obvious that there is a wide gap in regional house prices. This is clearly visible if you compare my place of birth with my current abode. Blackburn, like many areas outside the South East, has seen pretty much static house prices since 2008. Kingston upon Thames, like most other areas in London, took a bit of a breather in 2008 and then continued on its upward trajectory. I guess the interesting question is whether this is a permanent change or if the differences in regional prices will revert back to their historical average at some point. I can’t pretend to know the answer to that, but I do know prices in London are insane…

UK Postcode data for February 2015

The ONS have released the latest version of their postcode dataset and I have now uploaded it to my website. A few sanity checks suggest it is OK but let me know if you spot anything strange

How to beat a Strava PR on every ride

I think getting to, or maintaining, a healthy weight is fairly straightforward, in principle at least. Match your calorie intake with your calorie burning. Riders on the Tour de France eat 9000 calories a day, but don’t put on any weight for the obvious reason that they burn through all those calories. Eating less has never appealed to me, so the exercise side of the equation is the one I try to work on and it generally works OK for me.

But motivation can be a problem. Cycling is my exercise of choice and a winter of cold, wet and windy weather can rather reduce the will to get out on the road. I’ve found a few things to motivate me in the past, signing up with Endomondo (and trying to beat various personal bests), buying a new bike and training for the Ride London 100 to name a few.

Strava is the latest motivator. Every ride gives the opportunity to beat a PR on one segment or another, so there are many more chances to get a little boost from receiving a medal at the end of a ride. But sometimes, nothing. A ride of an hour may lead to no achievement.

But there is a way to almost guarantee a PR on every ride. First, sign up with veloviewer. This provides even more geeky information about every segment you’ve ridden. Next, filter the segment list for ones you’ve only ridden once or twice. Next, check the weather to find out the prevailing wind. Now find some segments where the wind will be behind you. Then plan your ride to include those segments. And finally, ride the route!

And voila, chances are you will beat one of your PRs on that ride. And even better, you’ll probably have ridden some new segments during your ride, which will now be in your list of potential PR segments.

I’ve been using this technique for the last few months and I’ve still got 140 segments within 5 miles of my house that I’ve ridden 2 or less times. Of course I’ll get bored of this at some point, but maybe I’ve already found my next motivation tool (aside from Ride London 2015), increasing my Eddington number…

UK house price data for December 2014

I’ve uploaded the latest Land Registry house price data, for December 2014, to my website. Prices seem to be gradually drifting upwards, as do the number of sales.

House price data for November 2014

I’ve uploaded the Land Registry sales data for November 2014 to my site.

Grading bike ride climbs

I’ve updated the route elevation page on doogal.co.uk so you can now grade climbs. It uses the same rating as Strava, which is based on the UCI climb categorization. Hopefully it will be useful if you can’t find a matching segment on Strava.

Non-geographic postcodes added to UK postcode list

I received a complaint that some postcodes were missing from my UK postcode list that were in the original ONS data. I was a little confused by this, since the import is pretty much automated. But looking at my import code I realised I was ignoring postcodes with no location information. I think initially I’d assumed these were postcodes with duff data so ignored them, but for completeness I’ve now added them to the list, adding a few thousand more postcodes. Since they have no associated location data, there isn’t much interesting information available for each of these postcodes but they may be useful for something… An example.

UK house sales October 2014

I’ve just finished uploading the latest Land Registry UK house sales data to my website. I then realised my annual percentage change calculation was wrong and have fixed that.

UK Postcode data November 2014

I’ve uploaded the latest UK postcode data to my site. There seem to be a few changes to the data (some codes for wards and districts have changed and LSOA data is now available for Scotland). I think I’ve found all the anomalies but let me know if you spot anything odd

More options when calculating route elevations

I’ve added a couple of options to my page for calculating route elevations. You can now select options to avoid highways and toll roads so it should be even more useful!

Goodbye Endomondo, hello Strava and VeloViewer

Back in the day I used to go for bike rides just for the fun of it. Then I discovered Endomondo and was able to analyse every part of a ride. And being a geek, that motivated me to ride more, try to ride faster and try to ride further. I could try to beat my best time for 10 miles or distance covered in an hour. But the number of awards was kind of limited, so my motivation started to flag. I got some more enthusiasm by training for RideLondon 100. But once I’d completed that (or to be more accurate, the 86 miles that I was allowed to ride), I was looking for something else to keep me moving, especially now the days are getting shorter and the weather is deteriorating.
I’d heard of Strava before but I’d discounted it because there was no app for my Windows Phone (what’s new right?). But then I realised Endomondo has the ability to export workouts which can then be imported into Strava. So I gave it a try. And I was immediately hooked. Rather than compare activity over a specific distance/time, I can compare efforts over the same bit of road, a segment. So for any ride I might pass through 20 or 30 segments and I generally beat a personal best on at least one of them. And that helps keep me going.
And for the ultimate geek experience, there’s VeloViewer. This runs on top of Strava and gives me an even more in depth view of my performance on segments. It tells me I have cycled on 1472 segments and I have a score of 86.4 (I have no idea if this is good or bad but it’s headed in an upwards direction which seems like a good thing)
VeloViewer was free but is now asking for £9.99 a year, with a pretty limited free version. This seems like a reasonable amount to pay for something so compelling. Strava also has a premium service but I haven’t seen anything in there that I need. My guess is that Strava will probably start to require premium membership to use their API fully which means any VeloViewer users will need to pay for their Strava account to use VeloViewer. I’d have thought that would be a no-brainer for Strava, since all VeloViewer users are the kind of people who are prepared to pay for a service and are therefore likely to cough up for Strava as well.
Anyway, that should keep me going during the long winter months. Maybe my next motivator will be my own little app running on top of Strava…

House price data now with annual change

The Land Registry sales data on my site now includes the annual price change. I thought this would smooth out the seasonal variations but the annual change is still quite volatile. Even so, it may be of interest.

UK house sales September 2014

The latest house price data from the Land Registry is available on my website and prices continue to defy gravity…

Unable to get property 'setState' of undefined or null reference in ckeditor.js

I’ve been working on the latest and greatest Business Optix product which dynamically creates lots and lots of HTML controls, some of which are CKEditor controls. Whilst testing the app and quickly navigating around it, I started getting an error “Unable to get property 'setState' of undefined or null reference” coming from deep in the bowels of CKEditor. Google astonishingly turned up nothing, but I remembered I’ve had trouble in the past with CKEditor when I didn’t explicitly destroy the editors. The fix was simple, like this

for (name in CKEDITOR.instances) {
  CKEDITOR.instances[name].destroy();
}

Property sales data for August 2014

I’ve uploaded the latest Land Registry data to my website. People comparing the data on my site to news stories like this may be wondering why my data shows a new all time average price, whereas the BBC say prices are yet to reach their previous peak of November 2007. I believe this is due to the Land Registry seasonally adjusting their figures whereas the average values on my site uses a geometric mean of the raw data.

UK property sales data for July 2014

The latest Land Registry data for property sales is now uploaded to my site. Not much can be read into a single month’s figures, but the average sale price has reached an all time high, which I guess pleases a government seeking re-election soon and probably dismays first time buyers.

UK Postcodes August 2014

I have uploaded the ONS postcode dataset for August 2014 to doogal.co.uk. Hopefully everything is in order, let me know if you spot any issues.

Land Registry June 2014 data

I’ve uploaded the Land Registry property sales data for June 2014 to doogal.co.uk. Enjoy!

Setting HttpResponse.StatusDescription silently failing

We recently received a complaint from one of our customers. We provide some fairly simple reporting functionality, that allows more technical users to write their own SQL queries. The customer was building a report and when there was a problem with his SQL, sometimes he’d get a detailed error message, but other times he’d get nothing.

When we try to execute a query and an exception is thrown we catch the exception and write the error message to HttpResponse.StatusDescription so it can be displayed in the browser. This can fail if the message is longer than 512 characters long, but this is fairly obvious since setting the StatusDescription property will throw an exception. That clearly wasn’t the problem here.

I finally managed to reproduce the problem but was still confused about what was causing the issue. Then I spotted the difference between the working case and the non-working case. The non-working case contained new line characters. Thinking about it, this was fairly obviously going to be a problem. The HTTP response would not be valid, since the status description header would be split over two lines. But it would certainly be preferable if .NET threw an exception in this case, rather than just silently failing to set the status description.

So our code now looks something like this

        context.Response.StatusCode = 500;
        context.Response.TrySkipIisCustomErrors = true;
        string description = ex.Message.Replace('\n', ' ').Replace('\r', ' ');
        if (description.Length > 512)
          description = description.Substring(0, 512);

        context.Response.StatusDescription = description;
        context.Response.ContentType = "text/plain";
        context.Response.Write("An error occurred - " + ex.Message);

Land Registry May 2014 data

I’ve uploaded the Land Registry data for May 2014 to doogal.co.uk. For all the talk of a house price bubble, the Land Registry data (arguably the most accurate of all the house price indices) doesn’t seem to show much movement at all over the last few months. Of course it’s a different story in London. There was a story about the housing insanity in Hackney a few months ago, and looking at the sales in East London does show prices shooting up over the last year.

Land Registry house price data for April 2014

The Land Registry house price data for April 2014 is now up on my site

ONS postcode data for May 2014 uploaded to doogal.co.uk

I’ve just uploaded the latest postcode data from the ONS to my site. There are over 2.5 million postcodes in there, alive and dead. My data checks suggest everything is in order, but let me know if you find a problem.

Downloading Javascript generated data

I have a number of web pages that generate some data in text areas using Javascript. The only way users could download this data was to copy and paste the contents of these text areas, but I wanted to add a download button to simplify the process. The problem is that this simply isn’t possible in Javascript. The only client-side solutions I’ve seen either require Flash or are not supported in all browsers.

So I came up with a slightly hacky and inefficient solution. The basic idea is to post the data to the server and get the server to return it to the client as a download. The HTML looks like this

      <form action="download.php" method="post">
        <div>
          <input type="hidden" name="fileName" value="locations.csv" />
          <input type="submit" value="Download" />
        </div>
        <textarea id="geocodedPostcodes" style="width:100%;" rows="20" name="data"></textarea>
      </form>

All that is needed is a hidden field that tells the server-side script what the download file name should be and a text area with a name of “data”.

The server-side script is pretty simple, it looks like this

<?php
  header('Content-Disposition: attachment; filename="' . $_POST["fileName"] . '"');

  // add data
  print($_POST["data"]);
?>

All it does is get the requested file name and echo back the data.

It’s seems a bit crazy (and a waste of bandwidth) that this seems to be the only way to achieve a seemingly simple task, but that looks to be the case. I’d be happy to be proved wrong.

Help me go on a bike ride

Last year I saw the various Ride London rides on the telly and rolling through Kingston and fancied doing it myself. Riding round London and Surrey on traffic-free roads is very appealing, compared to the usual stop-start, take your life in your hands experience of cycling round these parts. So the first chance I had, I applied in the ballot for the Ride London-Surrey ballot. And in January I heard I’d missed out on getting a place.

There was one more option. Sign up with a charity and raise some money and get a guaranteed place. So I decided to try and help out Cancer Research. Why Cancer Research? Primarily because cancer affects so many people at all stages of life but also, on a personal level, one of my partner’s best friends lost her life to cancer a couple of years ago, before she reached the age of 40.

I’ve set up a page for donations, added a link from my website and been amazed by the number of people who don’t know me who’ve already donated. If you’ve found this blog or my website useful, or are just feeling generous, then please consider donating some money. I will certainly appreciate it, as will Cancer Research.

Land Registry March 2014 data uploaded

I’ve uploaded the Land Registry house price data for March 2014 to my website. Now that probably all the sales data for 2013 has come in, it’s plain to see sales volumes were up in 2013 and prices continue to drift upwards

The perils of micro-optimisations

A debate has been raging on my website over the use of StringBuilder.AppendFormat in my exception logger code. OK, raging is something of an exaggeration, there have been two comments in two years. But the point made by two people is that rather than

error.AppendLine("Application: " + Application.ProductName);

I should be using

error.AppendFormat("Application: {0}\n", Application.ProductName);

Since this means I wouldn’t be using string concatenation, which is considered bad for performance reasons. My main reason for not doing anything about this is because I’m lazy, but also because the whole point of this code is that it only runs when an exception is thrown, which hopefully is a pretty rare event, so performance is not a major concern.

But then I wondered what the difference in performance is between these two approaches? So I wrote a little test application that looks like this.

    static void Main(string[] args)
    {
      for (int j = 0; j < 10; j++)
      {
        // try using AppendLine
        Console.WriteLine("AppendLine");
        StringBuilder error = new StringBuilder();
        Stopwatch sw = new Stopwatch();
        sw.Start();
        for (int i = 0; i < 1000000; i++)
        {
          error.AppendLine("Application: " + Application.ProductName);
        }
        sw.Stop();
        Console.WriteLine(sw.ElapsedMilliseconds);

        // try using AppendFormat
        Console.WriteLine("AppendFormat");
        error.Clear();

        sw.Restart();
        for (int i = 0; i < 1000000; i++)
        {
          error.AppendFormat("Application: {0}\n", Application.ProductName);
        }
        sw.Stop();
        Console.WriteLine(sw.ElapsedMilliseconds);
      }

      Console.ReadKey();
    }

The results from this app in milliseconds are as follows (reformatted for clarity)

AppendLine	307	315	321	372	394	370	289	298	300	296
AppendFormat	366	360	362	471	353	359	354	365	365	350

So which is quicker? Well it looks like AppendLine might be marginally quicker. But, much more importantly, who the feck cares? We are repeating each operation 1 million times and the time to execute is still less than half a second. Maybe you can pick holes in my test application, but again I would ask who the feck cares? Either approach is really fast.

And this is the main problem with trying to optimise this kind of stuff. We can spend huge amounts of time figuring out if one approach is quicker than another, but a lot of the time is doesn’t matter. Either the code runs quick enough using any sensible approach, or it’s hit so infrequently that even a really poor implementation will work.

Of course we should consider performance whilst writing code, but we should only use particular approaches when we know they are going to produce more performant code. A good example is the StringBuilder class. We can be pretty sure this is going to be better than using string concatenation, otherwise it wouldn’t exist in the first place. That said, if you’re concatenating two strings I really wouldn’t worry about it.

But the key to writing efficient code is to understand what is slow on a computer. Network operations are slow. Disk access is slow. Because of that, anything that requires large amounts of memory (meaning virtual memory i.e. disk access) is slow. Twiddling bits in memory is quick. Fast code is achieved by avoiding the slow stuff and not worrying about the quick stuff.

And once you’ve written your code and found it doesn’t run ask quick as you’d hoped, don’t jump in and replace calls to AppendLine with calls to AppendFormat, profile your application! Every time I profile an application, I’m always amazed at the causes of the performance bottleneck, it’s rarely where I thought it would be.

If you don’t have a profiler, use poor man’s profiling. There are also free profilers available, I quite liked the Eqatec Profiler which seems to be available from various download sites, although it’s no longer available from Eqatec. But whatever you do, don’t get into Cargo Cult Programming

Land Registry data for Feb 2014

I have uploaded the Land Registry house price data to doogal.co.uk.

There’s been a lot of talk in the press recently about there being a two speed housing market, London and the rest of the UK. You can see this illustrated fairly clearly if you first look at house prices in Blackburn then compare them with prices in West London.

Prices in Blackburn can be broken into three distinct periods. Prior to 2003, they were gently rising, probably in line with wage increases. Then in 2003 things went ballistic (I’m not sure of the trigger for that, although I’d guess it was easier access to mortgages). 5 years later in 2008, things ground to a halt, sales fell of a cliff and prices have been flat-lining ever since.

But look at West London and the only similarity is that sales volumes dropped off rapidly in 2008, but you’d never know that there was a financial crisis at all. Houses have been a one way bet for nearly 20 years. You’ve got to wonder how long it can go on.

Bluffers Guide to responsive design

A while back I spent a bit of time making doogal.co.uk more mobile friendly. I’d put it off for a long time primarily because I thought it would be really hard. But actually it turned out to be not too tricky. So here is my not so comprehensive guide to making your site mobile friendly with responsive design

The first thing to do is decide at what screen size your design will change from the normal design to the mobile design. My decision was that tablets should see the standard design but mobile phones should see the mobile design. So the media query I use for all my mobile CSS is

@media handheld, only screen and (max-width: 600px), only screen and (max-device-width: 600px) 

Better menus - My standard menus were tricky to use on a small screen, but fortunately they were built using styled unordered lists i.e. <ul></ul>, so I was able to use the Mobilemenu JavaScript library. This converts the list into a dropdown <select> which is much more useable on mobile devices.

Hide stuff – display:none is your friend. Most websites have bits on the page that may be useful but aren’t entirely essential. On a big screen we can get away with that, but on mobile devices it’s necessary to concentrate on the essential information. So hide anything that isn’t needed. I have several tables with many columns, but each row links through to more information, so I hid several of the columns since the tables didn’t render very well. The best approach to this appears to be CSS like the following

.postcodeTable  td + td { display: none;} 

No more table layouts – We’ve been told for years not to use tables for layout of our websites. But I’ve certainly been guilty of it, since it’s always easier to build a multi-column layout using a table. But now is when the chickens come home to roost. You may want two columns on the desktop, but on a mobile device, you’ll probably want to have the two columns stacked on top of each other, so those tables will need to be converted to div’s which float on the desktop and don’t on mobile devices.

Server side control – The solutions so far have all been client-side. I think this is generally the easiest way to deal with the issue, but there is certainly a good argument for saying content shouldn’t be getting pushed to the client if the client will never actually display it. If you’re using PHP on the back-end, Mobile Detect Library can be used to tailor your HTML before it leaves the server. One place where you may need to do this is adverts. Google’s T&Cs say you can’t hide adverts, so using display:none for them is probably a bad idea.

The beginning of the end of Metastorm BPM

It looks like development of Metastorm BPM has, if not stopped completely, at least slowed down. So I thought I’d write something about my thoughts about what was a big part of my professional career. If you want the full history, this isn’t it, have a look at Jerome’s book.

For me, it all started sometime in 1997. I was writing software for a firm called Bacon and Woodrow that sold actuarial software. It wasn’t really my kind of thing, but it was my first proper job, something to add to the CV. I got a call from a former colleague, Richard Kluczynski, who’d gone off to write his own software, then got a gig with a software house called Sysgenics. Before the days of mobile phones (or at least before I had one), I remember having to wander the streets of Epsom to find a phone box to call him back to discuss properly, away from the office. It sounded interesting but it wasn’t the right time for me as we were trying to get the first Windows version of our software out the door.

A few weeks or months later I got a call from a recruiter asking if I was looking for a new job and telling me about a company called Sysgenics. We were still trying to get our Windows version out the door, but I guess getting called about the same company twice peeked my interest. I remember looking at their website and getting pretty excited about the screenshots of some kind of graphical tool for building workflows called e-work. Before I knew it, I was in Wimbledon for an interview with Steve Brown and Jerome Pearce. And an hour later I was in the pub. This was obviously a great place to work!

And it was. We had no customers but some VC money to keep us ticking over. We were using the latest technologies (Delphi and MS Access!). Having no customers meant we could build stuff and break stuff without having to worry too much about upsetting people using the software, so we were always making a lot of progress.

Before long we were bought out by Metastorm. Looking back, that was actually a bit weird. Initially they seemed to be some massive software company but looking closer, the one product they sold, InForms, was clearly coming towards the end of its life, since it was tied into the dying Novell Groupware. But they had what we needed, money, and I guess we had what they needed, some modern software to sell.

The years flew by, six in fact. By that point we had quite a few customers, the little startup was a proper software house. There was structure and rules, forms to fill in, basically not really my scene anymore. So I flew the nest to work for a financial software house in central London. But a couple of years after that, Jerome asked me to join his little band of Metastorm consultants. So I built a shed and got to work building stuff on top of Metastorm e-work. Metastorm e-work became Metastorm BPM, we carried on calling it e-work… Metastorm started rewriting it from scratch in .NET, releasing it as version 9 (missing out version 8, some kind of off by one error I think).

I’d probably still be working in my shed for Jerome had the financial crisis not hit, caused major stress to our main client who then couldn’t pay us. So I went to Croydon, regretted it almost immediately and started working for myself. Back to the shed…

Then I started doing some work for Steve’s new company, Business Optix. That eventually became a full time job and is where I am now. Meanwhile Metastorm got bought out by OpenText. Given the price they paid, you’d think anyone who’d taken up their share options would have done well out of the deal, but you’d be wrong. Somebody must have made a nice chunk of money out of it, but it wasn’t the people who’d originally developed the software (this isn’t bitterness on my part, I never exercised the option on my shares).

But not content with one BPM tool, OpenText also bought Cordys and Global 360. I guess the writing was on the wall for two of those products at that point, why would a company want three BPM tools? Anyway, it looks like Metastorm BPM is one of the victims. You have to wonder why OpenText bought them in the first place, presumably not for the customer base, already fed up with having to rewrite their processes for version 9, now fuming that they need to rewrite again in some other system.

Land Registry sales data uploaded to doogal.co.uk

I’ve uploaded the latest Land Registry sales data, covering sales for January 2014, to my website. The good or bad news, depending on your point of view, is that prices continue to creep up. 

ONS postcode data for February 2014 available

I’ve just uploaded the latest postcode data from the ONS to my website. My checks suggests everything is OK with the data but let me know if you spot anything awry