Each line in the jamesgeo population cross (JPC) splits the area’s population in half.
Here at jamesgeo.com we’re great believers in testing our code. So that the JPC can be placed at any angle, we must test it at all angles.
This is the integration test for the jamesgeo population cross (JPC) of Great Britain. I’ve displayed the map in the original coordinates (WGS84) so that you can see that the lines are straight.
In the last post we came to the surprising conclusion that Newcastle is in the West. This is because the UK is tilted, yet we think of the East coast as running due North.
To match the population axes to our perceptions I have rotated the axes by 28 degrees. Generalising this creates the jamesgeo population cross, a crude indicator of population distribution.
- Find the long axis of the country
- Split the population in half twice – once parallel to this axis, and once perpendicular to it.
- Display in a local projection to get a true country shape (at the expense of the lines becoming curved, and the angle between the lines not looking like a right angle).
- Optional: Measure the distance (displacement) of the jamesgeo population cross from the centre (centroid) of the country.
Each line on the jamesgeo population cross splits the area’s population into two equal sections.
The JPC for Great Britain:
This is a much more realistic North-South divide:
- Birmingham, Lincoln and Grimsby are in the North
- Norfolk, Peterborough and Cardiff are in the South
- Newcastle and Leeds are in the East
- Portsmouth and Southampton are in the West
- Just NW of Leicester is the centre of Great Britain’s population density.
So every thing’s back where it belongs… just in time for the New Year.