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The largest city in each 10x10 degree latitude/longitude box

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Re: The largest city in each 10x10 degree latitude/longitude box

#151

Post by mjevans »

hammock wrote: post #139
caf wrote: post #25

I quibble with the description of the shapes bounded by 10 degrees of longitude and latitude as "rectangles" - they're not even planar shapes, and their adjacent sides certainly aren't at right angles. Some of them don't even have four sides. This bears considering when looking at the map, because some of those regions are much, much smaller than others.

You make a good point. What is an equal-area, tessellated shape that could be used in its place? I guess a triangle. Or one of these: https://upload.wikimedia.org/wikipedia/commons/thumb/6/67/Sp... https://upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Sp...

https://en.wikipedia.org/wiki/Geodesic_polyhedron

For just shapes the above is a nice visual start.

However a striking feature of the linked article is how frequently there's a major city right near a cell edge.

A more useful list might be constructed by some process involving assigning a "city" an imprint size based on population, and a surrounding 'metro area' based on absorbing any weaker cities that overlap until the process either repeats or is matched by a neighboring city.

A starting point for results that are already similar to that: https://en.wikipedia.org/wiki/Metropolitan_area

The US specific list: https://en.wikipedia.org/wiki/List_of_metropolitan_statistic...

Re: The largest city in each 10x10 degree latitude/longitude box

#152

Post by Delk »

leipert wrote: post #129
ronyfadel wrote: post #108

Earlier quoted context omitted.

That's handy! To be honest, SPARQL is definitely not easy to use.

I have worked with SPARQL professionally. The biggest problem: Quality if the data. Yes it is amazing, but if stuff is missing annotations, it is hard to get meaningful results.

Lots of things in the semantic web and RDF realm suffer from that. The technologies and ideas have been largely built under the (probably implicit) assumption that the data can be made perfect, but it never is.

Re: The largest city in each 10x10 degree latitude/longitude box

#153

Post by Delk »

runarberg wrote: post #119
qw wrote: post #116

Earlier quoted context omitted.

It also managed to include 5 Norwegian cities, but missed the largest city because it was in the same square as Berlin.

It’s fun to see that out of the Nordic capitals: Nuuk, Reykjavík, Tórhavn, and Helsinki made it; while Copenhagen, Oslo, and Stockholm didn’t.

I'm not even sure how accurate the map is, though. St. Petersburg is at the eastern end of the Gulf of Finland, and it would seem that it should be in the same square as Helsinki. St. Petersburg is definitely bigger.

I guess it ends up in the same square with Moscow and thus doesn't show up but either the map doesn't show the shoreline of the sea very accurately at all or it's wrong about the location of St. Petersburg.

Re: The largest city in each 10x10 degree latitude/longitude box

#154

Post by joshvm »

caf wrote: post #25

I quibble with the description of the shapes bounded by 10 degrees of longitude and latitude as "rectangles" - they're not even planar shapes, and their adjacent sides certainly aren't at right angles. Some of them don't even have four sides. This bears considering when looking at the map, because some of those regions are much, much smaller than others.

The South Pole is a particularly interesting case. Clearly the Pole itself is 90 South and the choice of longitude is arbitrary there. However, Amundsen-Scott station, which is a hundred odd metres away, happens to be at ~140 E (89.997553 S!) and due to the map projection it appears as if it's in a totally different place.

It would be interesting to see an interactive version with a free choice of meridians.

Re: The largest city in each 10x10 degree latitude/longitude box

#155

Post by rjeli »

foota wrote: post #122
bnjmn wrote: post #99

Earlier quoted context omitted.

This isn't exactly what you asked for, but it seems pretty relevant to your stated interests: https://www.jasondavies.com/maps/voronoi/capitals/

My head nearly exploded trying to position the globe in the rotation I wanted :-) Neat though, thanks for sharing!

Generally with orbit controls you can drag circles with your mouse to roll, taking advantage of the noncommutativity of SO(3)

Re: The largest city in each 10x10 degree latitude/longitude box

#156

Post by melvinroest »

ronyfadel wrote: post #108
philshem wrote: post #105

Earlier quoted context omitted.

You can even request a query from the community: https://wikidata.org/wiki/Wikidata:Request_a_query

That's handy! To be honest, SPARQL is definitely not easy to use.

For people that want an easy tutorial (series, 60 min.) on SPARQL, I found one here [1]. It definitely helped me.

[1] https://www.youtube.com/watch?v=nbUYrs_wWto&list=PLaa8QYrMzX...

Re: The largest city in each 10x10 degree latitude/longitude box

#157

Post by runarberg »

Delk wrote: post #153
runarberg wrote: post #119

Earlier quoted context omitted.

It’s fun to see that out of the Nordic capitals: Nuuk, Reykjavík, Tórhavn, and Helsinki made it; while Copenhagen, Oslo, and Stockholm didn’t.

I'm not even sure how accurate the map is, though. St. Petersburg is at the eastern end of the Gulf of Finland, and it would seem that it should be in the same square as Helsinki. St. Petersburg is definitely bigger. I guess it ends up in the same square with Moscow and thus doesn't show up but either the map doesn't show the shoreline of the sea very accurately at all or it's wrong about the location of St. Petersbu…

According to Wikipedia:

Helsinki has a population of 650,058 and is located at 60°10′15″N 24°56′15″E while;

Saint Petersburg has a population of 5,351,935 and is located at 59°56′15″N 30°18′31″E

Saint Petersburg is one quadrant south and one quadrant east of Helsinki, or the same quadrant as Moscow as you said.

The bay gets a little thin before Saint Petersburg, and there is a parallel passing exactly through it. I’m guessing that’s whats making Saint Petersburg appear more inline then it is, or—more accurately—makes the shoreline appear to be more to the west then it actually is.

Re: The largest city in each 10x10 degree latitude/longitude box

#158

Post by exidy »

pretendgeneer wrote: post #5

I was surprised by Leonora, Western Australia being there with it's population of 556 [1], I tried to find a bigger town in the area but couldn't. I wonder if that is the smallest town on that map? [1] https://en.wikipedia.org/wiki/Leonora,_Western_Australia

Apparently it's 401 now[1].

[1] https://all-populations.com/en/au/population-of-leonora.html

Re: The largest city in each 10x10 degree latitude/longitude box

#159

Post by doersino »

tantalor wrote: post #126
doersino wrote: post #115

Earlier quoted context omitted.

Right angles with regard to the latitude-longitude coordinate system, but not with regard to the surface of the earth. Recall that all meridians intersect at the poles.

Yes with regard to the surface of the earth. Take the lines tangent to the meridian & parallel at the point of intersection. Observe these lines are perpendicular. Hence the meridian & parallel meet at a right angle.

You’re right, I apologize for my smartass answer.

Re: The largest city in each 10x10 degree latitude/longitude box

#160

Post by roelschroeven »

tantalor wrote: post #138
roelschroeven wrote: post #130

Earlier quoted context omitted.

I'm not 100% sure about that. Are angles between circles on a sphere defined by the angles between their tangent lines? If it were true, you could for each point/meridian combination construct an infinite amount of different circles that would all meet at right angles with that meridian (just vary the circle's radius). That doesn't feel quite right. According to Wikipedia [1], "in spherical geometry, angles are defin…

It only matters what is the angle between the lines tangent to the curves at the point of intersection. Here's an example: https://www.desmos.com/calculator/is7mush1ma The red and blue circles are both perpendicular to the green circle at the origin.

OK, thanks, today I learned something new.
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