‘Western Sydney’ is a pretty politically and culturally charged term in Sydney, see: https://en.wikipedia.org/wiki/Westie_(person)
But, there is no real definition of what Western Sydney is. Seeing as it is essentially an opinon, I figured asking people is as good a way as any to define it.
After seeing this sweet post by Andy Woodruff and Tim Wallace, I realised I could use the use the tools generously uploaded by Nick Martinelli here to allow people to submit their definition of Western Sydney and then combine them.
The response was pretty good, and once I had removed all the continent sized cock and balls drawings, submissions for the Sydney in Nova Scotia etc. I had 119 definitions of Western Sydney to compare.
What was surprisingly difficult was finding a way to tally up how many definitions covered a given location. QGIS does not appear to have an integrated tool to achieve this. What I ended up doing was building an arbitrary hexagonal grid and then counting the number of the definitions that fell within each of the cells in this grid. To do that I had to build a python script using fiona and shapely, I’ll chuck the details of that code up later, it could help out anyone else who needs to count the number of polygons in another set of polygons.
The results are shown below. Each category represents the proportion of submitted definitions that agree a cell is in Western Sydney.
People seem to agree the eastern extent is somewhere between Lidcombe and Strathfield and the Western extent is somewhere between Penrith and the escarpment of the Blue Mountains. Compared to the northern and southern extent there is SIGNIFICANTLY less variation in opinion.
In general the spread of definitions to the north seems narrower than the south. The northern extent of 75% consensus area seems to follow the western train line almost exactly.
I also found it intersting that roughly equal numbers of people consider Campbelltown and parts of Epping to both be Western Sydney.
Edit: I have updated this post, removing references to the website people entered their definitions on that I was no longer using.