Tag: population

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GIS

Toronto’s Human Centre, part 2: by neighbourhood

Beware throwaway comments; that way overanalysis lies. This was a challenge.

Taking the 2006 neighbourhoods population into account, the human centre of Toronto is at 43.717955°N, 79.389828°W …

… pretty close to the one I’ve already worked out by ward.

Scraping the neighbourhood populations was hard. For the 140 neighbourhoods, the data is stored in a pdf with the URL like http://www.toronto.ca/demographics/cns_profiles/2006/pdf1/cpa124.pdf (in this case, 124; Kennedy Park, represent!). The population number is stored in a table on page 2 of each pdf. I used pdf2xml to convert the files into something parseable.

Of course, the tables weren’t exactly in the same place in every file, so I took a sample of 10% of the files, and worked out the X & Y coordinates of the population box. pdf2xml spits out elements like

<TOKEN sid="p2_s427" id="p2_w417" font-name="arialmt" serif="yes" fixed-width="yes" bold="no" italic="no" font-size="7.47183" font-color="#000000" rotation="0" angle="0" x="299.739" y="122.117" base="129.634" width="22.7692" height="9.94501">17,050</TOKEN>

Yes, I should have used an XML parser, but a Small Matter of Perl got me 126 out of the 140 matching. The rest I keyed in by hand …

Table after the jump.

Continue reading “Toronto’s Human Centre, part 2: by neighbourhood”
Categories
GIS

toronto’s human centre

Since it was trivial to calculate the centre of the city, I thought I’d do something a little more complex: calculate the centre of the city, weighted for population. I scraped the 2006 population data by ward from the City of Toronto: Ward Profiles pages; hooray for curl and regexes. Realising that I had no information on population distribution within wards, I made a good old engineering assumption: we could idealize the population as a point mass at the centroid of each ward, and then calculate the centre of mass by balancing moments around the X and Y axis. (I mean, c’mon – it’s the sort of thing we all think about daily … isn’t it? Guys … hello … anyone there?)

I’ll spare you the details until after the jump, but I calculate the human centre of Toronto to be at 43.717794°N, 79.390299°W – that’s in Blythwood Ravine, just south of Blythwood Road. We should have a picnic there …

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