question about accessing geometry from an sf object

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 at gmail.com

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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 at nhh.no
https://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en