[postgis-users] Grid of points inside Polygon

[James David Smith]

Remi,

Ok. Cool. I've set the below query running. On Monday I will also
attempt to get the original road lines file too. Let's see if we have
a result on Monday.
----------------------------------
CREATE TABLE lines_for_each_road AS
WITH all_lines AS (
SELECT *
FROM all_lines
),
cutted_lines AS ( --we cut the line to keep only part of lines inside
road_buffer
SELECT ST_Intersection(all_lines.the_geom,ukmajrdbuffer.geom) as
lines_cutted, direction
FROM ukmajrdbuffer, all_lines
WHERE ST_Intersects(ukmajrdbuffer.geom, all_lines.the_geom)=TRUE
),
cutted_lines_SN AS ( --this is the cutted lines which going from South to North
SELECT *
FROM cutted_lines
WHERE direction = 'SN'
),
cutted_lines_EW AS ( --this is the cutted lines going from East toWest
SELECT *
FROM cutted_lines
WHERE direction = 'EW'
),
points AS ( -- we take the intersection of EW  lines with SN lines ,
that is the points on the grid.
SELECT ST_Intersection(clSN.lines_cutted, clEW.lines_cutted) AS point
FROM cutted_lines_SN as clSN, cutted_lines_EW AS clEW
WHERE ST_Intersects(clSN.lines_cutted, clEW.lines_cutted)=TRUE --no
point ot compute an intersection if lines don't intersect
)
SELECT row_number() over() AS id  , point
FROM points ;
------------------------------------------
Thanks

James

On 15 November 2013 15:37, Rémi Cura <remi.cura at gmail.com> wrote:
>
> You should try to get the original road file, because i will be very easy to
> reapply some buffer and filtering to keep only major road.
> Yet, why not let it run during the week end?
>
> Cheers,
>
> Rémi-C
>
>
> 2013/11/15 James David Smith <james.david.smith at gmail.com>
>>
>> Hey Remi,
>>
>> Do you think before I try running the big query you have just sent me,
>> that I should go back and try to get the original file of uk roads? I
>> mean the very original file that has not had any buffers applied or
>> any merging done.
>>
>> Or shall we just go for it and see if it has finished when I come into
>> work on Monday?! haha.
>>
>> Thanks
>>
>> James
>>
>> On 15 November 2013 14:01, Rémi Cura <remi.cura at gmail.com> wrote:
>> > Outch,
>> > you have only 8 roads in GB? =)
>> >
>> > This is not going to go fast till you don't have some dozens k's of
>> > roads.
>> >
>> > I'm guessing you are not at will to send those roads?
>> >
>> >
>> > The next step will be (when you'll be sure everything is OK)
>> >
>> >
>> > CREATE TABLE lines_for_each_road AS
>> > WITH all_lines AS (
>> > SELECT *
>> > FROM all_lines
>> > ),
>> > cutted_lines AS ( --we cut the line to keep only part of lines inside
>> > road_buffer
>> > SELECT ST_Intersection(all_lines.the_geom,ukmajrdbuffer.geom) as
>> > lines_cutted, direction
>> > FROM ukmajrdbuffer, all_lines
>> > WHERE ST_Intersects(ukmajrdbuffer.geom, all_lines.the_geom)=TRUE
>> > ),
>> > cutted_lines_SN AS ( --this is the cutted lines which going from South
>> > to
>> > North
>> > SELECT *
>> > FROM cutted_lines
>> > WHERE direction = 'SN'
>> > ),
>> > cutted_lines_EW AS ( --this is the cutted lines going from East toWest
>> > SELECT *
>> > FROM cutted_lines
>> > WHERE direction = 'EW'
>> > ),
>> > points AS ( -- we take the intersection of EW  lines with SN lines ,
>> > that is
>> > the points on the grid.
>> > SELECT ST_Intersection(clSN.lines_cutted, clEW.lines_cutted) AS point
>> > FROM cutted_lines_SN as clSN, cutted_lines_EW AS clEW
>> > WHERE ST_Intersects(clSN.lines_cutted, clEW.lines_cutted)=TRUE --no
>> > point ot
>> > compute an intersection if lines don't intersect
>> > )
>> > SELECT row_number() over() AS id  , point
>> > FROM points ;
>> >
>> >
>> >
>> >
>> >
>> > Cheers,
>> >
>> > Rémi-C
>> >
>> >
>> >
>> > 2013/11/15 James David Smith <james.david.smith at gmail.com>
>> >>
>> >> Hey Remi,
>> >>
>> >> I'll do a few checks and get back to you. Maybe I did something wrong
>> >> because I set this query going on my local PostgreSQL installation but
>> >> also on our Linux Cluster machine which is much more powerful. And it
>> >> finished on my local installation BEFORE the cluster. So maybe I did
>> >> something wrong on the local query.
>> >>
>> >> The query that has finished took about 1 hour.
>> >> The query on our cluster is still running.
>> >>
>> >> select count(*) from ukmajrdbuffer = 8
>> >> This is because before I was given the data the roads buffer had
>> >> already been dissolved unfortunately.
>> >>
>> >> James
>> >>
>> >>
>> >>
>> >>
>> >> On 15 November 2013 13:43, Rémi Cura <remi.cura at gmail.com> wrote:
>> >> > Good !
>> >> >
>> >> > Something is strange with the result,
>> >> > you get only 190k lines intersecting road buffer,
>> >> > it is very few , I expected at least 10times this!
>> >> > How many time took this computing by the way?
>> >> >
>> >> > How many road buffer geom do you have ? (select count(*) from
>> >> > ukmajrdbuffer
>> >> > ).
>> >> >
>> >> > Cheers,
>> >> > Rémi-C
>> >> >
>> >> >
>> >> > 2013/11/15 James David Smith <james.david.smith at gmail.com>
>> >> >>
>> >> >> Hey.
>> >> >>
>> >> >> Yes, it's done. Was just getting some lunch! :-)
>> >> >>
>> >> >> select count(*) from lines_for_each_road
>> >> >> Result = 187033
>> >> >>
>> >> >> I have also just ran 'VACUUM ANALYZE' on the tables
>> >> >> 'lines_for_each_road' as well as the table 'all_lines'
>> >> >>
>> >> >> I also can confirm that I have ran the following commands:
>> >> >>
>> >> >> CREATE INDEX all_lines_index ON all_lines USING GIST ( the_geom )
>> >> >> CREATE INDEX ukmajrdbuffer_index ON ukmajrdbuffer USING GIST (geom);
>> >> >>
>> >> >> Should we now uncomment this line from the previous query?
>> >> >>
>> >> >> "  SELECT row_number() over() AS id--,*  "
>> >> >>
>> >> >> Thanks again Remi,
>> >> >>
>> >> >> James
>> >> >>
>> >> >>
>> >> >>
>> >> >> On 15 November 2013 13:14, Rémi Cura <remi.cura at gmail.com> wrote:
>> >> >> > Also if you do have indexes,
>> >> >> > can you run a "VACUUM ANALYZE", so that the indexes will be used?
>> >> >> >
>> >> >> > Cheers,
>> >> >> >
>> >> >> > Rémi-C
>> >> >> >
>> >> >> >
>> >> >> > 2013/11/15 Rémi Cura <remi.cura at gmail.com>
>> >> >> >>
>> >> >> >> It should be finished by now,
>> >> >> >> can you check you have geom indexes on :
>> >> >> >> "ukmajrdbuffer.geom" and  "all_lines.the_geom"
>> >> >> >>
>> >> >> >>
>> >> >> >> How many geoms do you have in "ukmajrdbuffer"?
>> >> >> >>
>> >> >> >> Cheers,
>> >> >> >> Rémi-C
>> >> >> >>
>> >> >> >>
>> >> >> >> 2013/11/15 Rémi Cura <remi.cura at gmail.com>
>> >> >> >>>
>> >> >> >>> Hey Sandro,
>> >> >> >>>
>> >> >> >>> Thanks for this, it is at least twice faster =)
>> >> >> >>>
>> >> >> >>> Cheers,
>> >> >> >>> Rémi-C
>> >> >> >>>
>> >> >> >>>
>> >> >> >>>
>> >> >> >>>
>> >> >> >>> 2013/11/15 James David Smith <james.david.smith at gmail.com>
>> >> >> >>>>
>> >> >> >>>> Thanks both. Geometries now fixed.
>> >> >> >>>>
>> >> >> >>>> The query 'CREATE TABLE lines_for_each_road....' has now been
>> >> >> >>>> set
>> >> >> >>>> running. Will report back when it's done. I suspect it may take
>> >> >> >>>> a
>> >> >> >>>> while!
>> >> >> >>>>
>> >> >> >>>> James
>> >> >> >>>>
>> >> >> >>>> On 15 November 2013 11:03, Sandro Santilli <strk at keybit.net>
>> >> >> >>>> wrote:
>> >> >> >>>> > On Fri, Nov 15, 2013 at 11:50:42AM +0100, Rémi Cura wrote:
>> >> >> >>>> >> Yep, maybe something like
>> >> >> >>>> >>
>> >> >> >>>> >> UPDATE ukmajrdbuffer SET the_geom = ST_MakeValid(the_geom)
>> >> >> >>>> >> WHERE ST_IsValid(the_geom) = FALSE
>> >> >> >>>> >
>> >> >> >>>> > ST_MakeValid internally checks for ST_IsValid, so no need
>> >> >> >>>> > to add the condition (which would run the test twice).
>> >> >> >>>> >
>> >> >> >>>> > --strk;
>> >> >> >>>> > _______________________________________________
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>> >> >> >>>
>> >> >> >>
>> >> >> >
>> >> >> >
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