flickr_gis_project's Introduction

gis project

analyzing flickr photo data by geo-locations of these photos, by using GIS technologies, including PostgreSQL, PostGIS, QGIS

Route popularity

Use the flickr photo data to show the popularity of each route according to how many photos have been taken along the route within a 25m buffer. You should normalise this by route length (i.e. photos per metre).

drop table if exists route_line_length;
create table route_line_length as 
select geom, st_length(geom) as line_length, 'routea' as route_name  from routea 
union all 
select geom, st_length(geom) as line_length, 'routeb' as route_name  from routeb
union all 
select geom, st_length(geom) as line_length, 'routec' as route_name  from routec;


drop table if exists route_length;
create table route_length as 
select route_name, sum(line_length) as route_length
from route_line_length
group by route_name;


select * from route_length;
select route_length.route_name, 
route_photo_count.photo_count/route_length.route_length popularity,
route_length.route_length, 
route_photo_count.photo_count
from route_length
join (
	select route_name, count(*) as photo_count
	from (
		SELECT flickr_edin.*, route.route_name
		FROM flickr_edin 
		JOIN route_line_length as route ON 
		ST_INTERSECTS(flickr_edin.geom,ST_BUFFER(route.geom,25))
	) photo_over_route
	group by route_name
) route_photo_count
on route_length.route_name = route_photo_count.route_name
order by route_photo_count.photo_count/route_length.route_length desc;

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