Thanks. Solved!
That worked like a charm.
Exactly what i wanted.
Andreas
2010/10/21 Nicklas Avén
> Ok
>
> still don't get the second query. If I understand you right you could try
> this:
>
> CREATE TABLE borddisttest2 AS
> select a.gid, a.cell, MIN(ST_Distance(a.centroid, b.the_geom)) AS dist
Ok still don't get the second query. If I understand you right you could try
this: CREATE TABLE borddisttest2 ASselect a.gid, a.cell,
MIN(ST_Distance(a.centroid, b.the_geom)) AS distance FROM pgfinal2008 a,
cshapes b, cshapes c WHERE a.gwcode != b.gwcode AND b.gwsyear <= 2008 AND
b.gweyear >= 2
Ok. I will try to explain more in detail.
I have a vector grid consisting of 64818 grid cells. Each of these cells are
stored in the pgfinal2008 table, with two geometries variables: centroid
(point) and cell (polygon).
Each grid cell have a gwcode variable which is the country code.
In addition i
hmm, I have to admit I don't really understand what you are trying to do, but
there are some thingsI don't think you really mean. select a.gid,
MIN(ST_Distance(a.centroid, b.the_geom)) AS distance FROM pgfinal2008 a,
cshapes b, cshapes c WHERE a.gwcode != b.gwcode AND b.gwsyear <= 2008 AND
b.gw
Thanks.
I have found a way to do this calculation.
However, since i gave 64818 cells and almost 200 countries, the distance
from every cell to every country is calculated before the minimum distance
is selected.
This takes awful lot of time.
Any ideas on how to increase the performance?
DROP TABL
Hi You can not cast to geography that way (if I haven't missed something
essential)
And if you could you would mix geometry and geograph type in ST_Distance, which
wouldn't work. St_Distance for geometry vs geography uses totally differnt
algorithms. The geography calculations is far more advanc
Hi
Thanks,
I will give it a try.
The reason I used the geography types in the distance query, were to get the
distance in meters instead of degrees.
Andreas
2010/10/13 Nicklas Avén
> Hi
>
> As I understand you you want to get the distance from each cell to the
> closest neighbour country. The
Hi As I understand you you want to get the distance from each cell to the
closest neighbour country. Then, why don't you just query the distance from
your cell to closest country with other gwcode?Maybe something like: Create
table borddisttest asSelect ST_Distance(st_collect(b.the_geom), c.cent
Hi all,
I have two datasets. On is a quadrate grid, and the other is the boundaries
of all countries.
What i want to do is to measure the distance from each centroid of the grid
cells to the nearest border, but not all borders. Only the international.
First i convert my country polygon dataset in
