[postgis-users] Grid of points inside Polygon

[Rémi Cura]

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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