[R-sig-Geo] Semi-join?

Tim Keitt tke|tt @end|ng |rom utex@@@edu
Tue May 7 22:43:55 CEST 2019


Thanks. Works now. It was an issue with map projections.

THK

On Tue, May 7, 2019 at 3:18 PM Tim Keitt <tkeitt using utexas.edu> wrote:

>
>
> On Tue, May 7, 2019 at 1:39 PM Edzer Pebesma <
> edzer.pebesma using uni-muenster.de> wrote:
>
>>
>>
>> On 5/7/19 8:29 PM, Tim Keitt wrote:
>> > I keep finding things that are trivial in sql are not so in R, so
>> perhaps
>> > you can help me out.
>> >
>> > What would be the way in the 'sf' package to retain only polygons from
>> one
>> > coverage that intersect points in another coverage? I think that's a
>> > semi-join.
>> >
>> > Roughly: 'select a.* from polys a, points b where st_intersects(a.geom,
>> > b.geom)'
>>
>> a[b,]
>>
>> # or
>>
>> st_join(a, b, left = FALSE) # no left join gives you inner join
>>
>
> Hmm... tried this and for some reasons it was not giving me what I wanted.
> I will investigate.
>
> THK
>
>
>>
>> >
>> > Thanks.
>> >
>> > THK
>> >
>>
>> --
>> Edzer Pebesma
>> Institute for Geoinformatics
>> Heisenbergstrasse 2, 48151 Muenster, Germany
>> Phone: +49 251 8333081
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>> >> matters at https://links.utexas.edu/rtyclf.                        <<
>>
>
>
> --
> Timothy H. Keitt
> Professor of Integrative Biology and
> Associate Chair for Undergraduate Education
> http://www.keittlab.org/
>


-- 
Timothy H. Keitt
Professor of Integrative Biology and
Associate Chair for Undergraduate Education
http://www.keittlab.org/

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