The latest outputs from researchers, alumni and friends at the UCL Centre for Advanced Spatial Analysis (CASA).
Today, I needed a JavaScript equivalent of Ruby’s Array#compact (which returns the array stripped of any nil values). A standard JavaScript implementation looks like this: Array.prototype.compact = function() { var x, _i, _len, _results; _results = []; for (_i = 0, _len = this.length; _i < _len; _i++) { x = this[_i]; if (x != […]
Continue reading »Preamble In the last few years, Objective-C has become enormously DRYer. For example: in the past, adding a property to a class meant adding several of: an ivar, a @property, a @synthesize, a getter/setter, and a release call in dealloc. Worse, renaming or deleting the property meant updating all these. This was error-prone busywork, and […]
Continue reading »For Cocoa developers: I’ve just put a small category on NSMutableAttributedString on Github. It applies *bold*, /italic/, _underline_, -strikethrough-, ^superscript^ and ~subscript~ styles, and handles */nested/* and *overlapping /styles* properly/. More details at https://github.com/jawj/NSMutableAttributedString-InlineStyles
Continue reading »For reasons that may become clearer in future, I needed to use a bandpass filter in an iOS app. The DSP part of Apple’s Accelerate framework makes this lightning fast both for the programmer to implement and for the machine to execute … if the programmer knows how use vDSP_deq22, which is documented, at best, […]
Continue reading »For reasons that may become clearer in future, I needed to use a bandpass filter in an iOS app. The DSP part of Apple’s Accelerate framework makes this lightning fast both for the programmer to implement and for the machine to execute … if the programmer knows how use vDSP_deq22, which is documented, at best, […]
Continue reading »I recently posted a HOWTO based on my experience moving a Xen domU from Linode to my own Xen Dom0 setup at Hetzner. Since this machine is only a development server, I more recently decided to turn the same machine into a VMware VM, running locally (in VMware Fusion 4 on my MacBook Pro). Here, […]
Continue reading »I recently posted a HOWTO based on my experience moving a Xen domU from Linode to my own Xen Dom0 setup at Hetzner. Since this machine is only a development server, I more recently decided to turn the same machine into a VMware VM, running locally (in VMware Fusion 4 on my MacBook Pro). Here, […]
Continue reading »I’ve been playing with the much-enhanced raster support in PostGIS 2.1 in the last few days. Amongst other things I’ve been producing maps with ST_MapAlgebra, which has changed a little since 2.0. The example callback function in the documentation is somewhat unhelpfully bare-bones: it always returns 0, touching none of its arguments. So here’s an […]
Continue reading »I’ve been playing with the much-enhanced raster support in PostGIS 2.1 in the last few days. Amongst other things I’ve been producing maps with ST_MapAlgebra, which has changed a little since 2.0. The example callback function in the documentation is somewhat unhelpfully bare-bones: it always returns 0, touching none of its arguments. So here’s an […]
Continue reading »Since light can affect happiness, two important pieces of environmental data I add to the Mappiness data set during analysis are: (1) whether a response was made in daylight; and (2) day length when and where the response was made. To derive these, I need the date, time and location of the response, and sunrise […]
Continue reading »Since light can affect happiness, two important pieces of environmental data I add to the Mappiness data set during analysis are: (1) whether a response was made in daylight; and (2) day length when and where the response was made. To derive these, I need the date, time and location of the response, and sunrise […]
Continue reading »We have an old MacBook (the original white Intel model from 2006) running EyeTV as our telly. Apple’s Magic Trackpad makes a handy remote control for this setup. Unfortunately, Bluetooth on the old MacBook is highly temperamental. Built-in Bluetooth regularly fails: out of the blue, the Mac decides that it has no Bluetooth module after […]
Continue reading »We have an old MacBook (the original white Intel model from 2006) running EyeTV as our telly. Apple’s Magic Trackpad makes a handy remote control for this setup. Unfortunately, Bluetooth on the old MacBook is highly temperamental. Built-in Bluetooth regularly fails: out of the blue, the Mac decides that it has no Bluetooth module after […]
Continue reading »We have an old MacBook (the original white Intel model from 2006) running EyeTV as our telly. Apple’s Magic Trackpad makes a handy remote control for this setup. Unfortunately, Bluetooth on the old MacBook is highly temperamental. Built-in Bluetooth regularly fails: out of the blue, the Mac decides that it has no Bluetooth module after […]
Continue reading »When converting coordinates between WGS84 (GPS) and OSGB36 (UK National Grid), using OSTN02 can gain us a few metres in accuracy over the basic parametric transformation provided by PostGIS’s st_transform via PROJ.4. Happily, Ordnance Survey now distribute an NTv2 version of the OSTN02 transformation, courtesy of the Defence Geographic Centre, which can be used by […]
Continue reading »When converting coordinates between WGS84 (GPS) and OSGB36 (UK National Grid), using OSTN02 can gain us a few metres in accuracy over the basic parametric transformation provided by PostGIS’s st_transform via PROJ.4. Happily, Ordnance Survey now distribute an NTv2 version of the OSTN02 transformation, courtesy of the Defence Geographic Centre, which can be used by […]
Continue reading »I recently needed to calculate a SHA1 hash in an iOS app. In iOS4+ it’s possible to use CommonCrypto, but Mappiness has always supported iOS3. I therefore added NSData and NSString categories to a public domain C implementation instead. This remains public domain: do with it what you will. It relies on a hex-encoding category […]
Continue reading »PostGIS 2 has some exciting new goodies — including raster support — that I’m keen to use in the analysis of Mappiness data. But the PostGIS package provided by Ubuntu 12.04 is still only at version 1.5, and the GEOS and GDAL packages are also too old to support the new version. So — this […]
Continue reading »PostGIS 2 has some exciting new goodies — including raster support — that I’m keen to use in the analysis of Mappiness data. But the PostGIS package provided by Ubuntu 12.04 is still only at version 1.5, and the GEOS and GDAL packages are also too old to support the new version. So — this […]
Continue reading »I’ve just released Spindlytext on Github. It’s the library that powers the live data display in Pigeon Sim, by creating KML linestrings in the shape of letters. It looks like this:
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Update, 10 February: Sorry for some serious reliability issues over the last few days. The streaming server is now hosted in-house at CASA, which should be a lot more robust. At CASA we’ve been looking at using a Kinect or three in our forthcoming ANALOGIES (Analogues of Cities) conference + exhibition. We’ve been inspired in […]
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There are plenty of ways to get spatial data from a PostGIS database into a Processing sketch. You can export to CSV or SVG and load it from there; you can query the database directly; or, depending on context, you might choose to generate Processing commands directly, which is the route I went to display […]
Continue reading »Need to protect something with a passcode in an iPhone app you’re developing? Then you may find my MIT-licensed passcode view controller — as seen in the mappiness app and in the short screencast below — of use. See Github for the code and (scant) documentation. Download video as MP4, WebM, or Ogg.
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Imagine you want compare various locations in terms of the availability of a certain type of environment, such as fresh water. You might want to use a measure of the proximity of that environment — such as the nearest neighbour distance. You might want to use a measure of the quantity of that environment in […]
Continue reading »Updated May 2012 for Lion The secret to getting the MySQL gem to install and function with Ruby 1.9.x on Snow Leopard or Lion is: Install MySQL using the 64-bit .DMG package installer from dev.mysql.com Install Ruby using RVM or (preferably) rbenv Add …
Continue reading »Ever noticed how, in Google Earth, marker pins that overlap each other spring apart gracefully when you click them, so you can pick the one you meant? And ever noticed how, when using the Google Maps API, the exact same thing doesn’t happen? This…
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