A common function in standard GIS software enables users to create a raster surface and extract values or clip it based on a set of polygons. This may be used in cases where you want analysis to be constrained to within a town’s boundaries or a coastline. This tutorial will outline how to create a surface using kernel density estimation (KDE) and then clip the surface so that it is constrained within the City of London Boundary.
Data Requirements:
City of London Boundary Shapefile: Download (requires unzipping).
Background:
In some cases it is necessary to conduct the same analysis multiple times on either the same or different data. In such circumstances it is worth writing a function to simplify the code. In this example the location quotient provides a simple calculation easily written in to a function.
The location quotient (LQ) is an index for comparing a region’s share of a particular activity with the share of that same activity found at a more aggregate spatial level (a good book on this kind of thing is Burt et al.). In this example we take a shapefile of London Boroughs that contains information on the population of each borough and the percentage of sports participation in each borough. In this case there is little point in calculating the LQ as the percentage alone would be more meaningful. The focus here is how to undertake the methods, not their appropriate use, or the validity of the results.
Data Requirements:
London Sport Participation Shapefile: Download (requires unzipping)
Install the following packages (if you haven’t already done so):
This is an updated version of my Making Maps with R tutorial. I think the code is lot simpler and it also includes some data for you to play around with.
Background:
Spatial data are becoming increasingly common, as are the tools available in R to process it. Of course one of the best ways of visualizing spatial data is through a map. Maps need to be well thought out. Not least, the selected colours need to be appropriate and sufficient context is provided through the use of a legend, title, scale bar and north arrow. The worksheet will demonstrate how to produce a map with R that includes all these elements.
Data Requirements:
London Sport Participation Shapefile. Download (requires unzipping)
Install the following packages (if you haven’t already done so):
When I was digging around some back-up files on my computer I came across this “How to…” published by the Guardian Newspaper in 2007. With many new geography students starting their respective courses in the coming weeks and many potential students considering applications to the subject in the coming months this may prove a useful guide. It’s a pretty good summary of the discipline (although I don’t know many human geographers interested in trams and of course there is no mention of GIS). Click here, or image, for full size.
In case you were wondering, to my knowledge, geographers still haven’t worked out why the sea fits so snugly around the coastline…
Before I dust down my corduroy jacket in preparation for the geography conference season, the article reminds me of the “what is geography?” question I prepared an answer for when applying for my undergrad. degree. If only I had thought of an answer as concise as Starbucks…
Last week I heard that the London School of Economics Geography Department was disposing of its maps and that anyone interested was free to rescue them. My first reaction was one of surprise as maps are one of the few things geographers are associated with, so it doesn’t seem right to have a geography department without a map room. My more rational side, however, understands that a change of research priorities within geography, combined with the fact that all up to date maps are now stored digitally probably means that the map room drawers have remained shut for a number of years. As universities expand there is an increasing demand for space and the “use it or lose it” policy is likely to apply.
So it fell to a number of enthusiasts to save the maps. I think the majority have been rescued and will be given new life as posters, artworks or simply keepsakes to be pulled out and admired on a rainy day. Rifling through the maps was a bit like going through an old photo album. Snapshots from the past, such as maps showing the narrow air corridor in 1970s Germany
For something closer to home, I picked up some really nice maps from the “Phillips Series of Comparative Wall Atlases” (dated 1956) that show the summer and winter temperatures across the British Isles. I suspect that today we can add a couple of degrees to many of the contour lines drawn on the maps.
My favorite find is a couple of Ordnance Survey maps of the Greenwich Area dated 1917, though some lucky person had made off with the rest of London! Highlights from the maps include the “Thames Soap and Candle Works”
and detailed outlines of the housing.
If anyone knows what the colours mean I would be interested in hearing from them…
I think it is a real shame that such a great collection of maps has had to be broken up and I suspect LSE Geography will not be the last to send its maps to recycling. Still every cloud has a sliver lining and I am now trying to find the wall space to hang my newly acquired maps!
Thanks to Ollie O’Brien for the tip off about the map room giveaway.
Just for a bit of fun and to help those of us with interests in all things geographical, spatial, GIS, maps and cartographic (I could go on…), I thought I would add “geo” to the usual Follow Friday (#ff) twitter hashtag to create #ffgeo. So if you have particularly enjoyed the geo-related tweets from one or several people this week, list their user names and include the #ffgeo hashtag so that fellow lovers of all things geo will know to check them out.
It may not take off, or it could be come a weekly event. Either way you can monitor progress below or here.
I hadn’t seen this video before. It demonstrates one of the earliest attempts at automated cartography for the display of temporal spatial data. The video shows the urban growth of Lansing at 5 yearly intervals from between 1850 and 1965 and was produced by Allan Schmidt at the Michigan State University Urban Regional Research Institute. The visualisation was produced with the synergraphic mapping system (SYMAP) developed by Howard Fisher in the mid 1960s. More details and a fully downloadable version can be found here. A presentation on SYMAP is available here. The sequence starts with a slow version of two minutes forty-five seconds before repeating the sequence more rapidly in forty-five seconds, and finally in five seconds.
Embedded below is a high resolution version of John Snow’s 1854 map of the Broad Street (now Broadwick Street) cholera outbreak. Widely cited as the one of the first (and arguably best) examples of using spatial analysis in epidemiological studies, Snow’s map holds a special place in the hearts of those using spatial analysis to improve people’s lives.
About the map: I found this map on the UMapper website and am therefore indebted to andreit for uploading it. Each black bar on the map represents a death from cholera and these can be clearly seen to cluster around the pump (red dot). A much more detailed explanation is provided by the UCLA Department for Epidemiology.
Much of the research we do in UCL Geography and CASA relates to London. One of the most interesting aspects of the city is its growth and development (you can see changes in London’s population density here). I was therefore excited to stumble on a scanned copy of “Maps of Old London” by Geraldine Milton (1908) (pdf or archive.org link). The book contains some great maps of London dating from as far back as the 16th Century. I have included several maps from the book below.
As I have mentioned before, archive.org provides some amazing resources for free download. I thought I would have a look to see what it had in the way of old atlases and I wasn’t disappointed. Here are a couple of my favorites: The Reynold’s Universal Atlas was published in the 19th century and includes over 400 maps an diagrams covering topics such as astronomy, vegetation, geology and the laws of matter and motion. Sadly many of the illustrations are spread over two pages but all are brilliant quality and make many of our contemporary maps appear dull by comparison. The “Tidal Chart of the World” taken from the atlas is shown below.
My second favorite is Justus Perthes’ Atlas Antiquus which is a pocket atlas of the ancient world. What is so great about this map is the fact that it has been scanned at very high resolution. The pdf is therefore >300mb! It includes some detailed maps of Rome and Athens as well as Northern Europe, North Africa, Spain and the Mediterranean. I have included the map of the UK and Ireland below. It would appear that this is part of a series of scanned atlases so there may be more to come.
