[R-sig-Geo] question about accessing geometry from an sf object

[Roger Bivand]

Hi Erin,

Maybe consider st_coordinates() to get a matrix of coordinates, 
preferably from st_geometry() of the "sf" object, as hard-coding the name 
of the column containing the "sfc" object might be affected in some cases 
by a different name. Then subset the matrix as you wish.

Hope this helps,

Roger

On Sun, 1 Aug 2021, Erin Hodgess wrote:

> Hello!
>
> I have the following sf object:
>
>> bt.cent
> Simple feature collection with 8 features and 1 field
> Geometry type: POINT
> Dimension:     XY
> Bounding box:  xmin: -105.0746 ymin: 38.97641 xmax: -104.7917 ymax: 39.82494
> CRS:           +proj=longlat +datum=WGS84 +no_defs
>   rnorm.10.                   geometry
> 1  0.3297790 POINT (-105.0746 38.97641)
> 2         NA POINT (-104.7917 38.97641)
> 3 -1.0734667 POINT (-105.0746 39.25925)
> 4         NA POINT (-104.7917 39.25925)
> 5 -0.1284898  POINT (-105.0746 39.5421)
> 6 -0.4071287  POINT (-104.7917 39.5421)
> 7         NA POINT (-105.0746 39.82494)
> 8  1.4171128 POINT (-104.7917 39.82494)
>
> And I am accessing the geometry (to build covariances) as:
>> bt.cent$geometry[[1]][1]
> [1] -105.0746
>> bt.cent$geometry[[1]][2]
> [1] 38.97641
>>
>
> Is that the best way to handle the geometry items, please?
>
> Thanks in advance,
> Sincerely,
> Erin
>
>
> Erin Hodgess, PhD
> mailto: erinm.hodgess using gmail.com
>
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>
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-- 
Roger Bivand
Emeritus Professor
Department of Economics, Norwegian School of Economics,
Postboks 3490 Ytre Sandviken, 5045 Bergen, Norway.
e-mail: Roger.Bivand using nhh.no
https://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en