Use sf polygon object as window in spatstat

Question

Hello all potential helpers,

I have a SpatialPolygonDataFrame object obtained from the tigris package and I would like to use it as a polyg

Answer 1

just want to note here that coercion methods for sf classes are now registered (if that's the right word) by the sf package. I don't fully understand the R magic that finds methods, but it does work.

library(sf)
library(spatstat)

> methods(as.owin)
 [1] as.owin.boxx                    as.owin.data.frame              as.owin.default                 as.owin.distfun                
 [5] as.owin.dppm                    as.owin.funxy                   as.owin.im                      as.owin.influence.ppm          
 [9] as.owin.kppm                    as.owin.layered                 as.owin.leverage.ppm            as.owin.linfun                 
[13] as.owin.linnet                  as.owin.lintess                 as.owin.lpp                     as.owin.lppm                   
[17] as.owin.msr                     as.owin.MULTIPOLYGON*           as.owin.nnfun                   as.owin.owin                   
[21] as.owin.POLYGON*                as.owin.ppm                     as.owin.ppp                     as.owin.psp                    
[25] as.owin.quad                    as.owin.quadratcount            as.owin.quadrattest             as.owin.rmhmodel               
[29] as.owin.sf*                     as.owin.sfc*                    as.owin.sfc_MULTIPOLYGON*       as.owin.sfc_POLYGON*           
[33] as.owin.SpatialGridDataFrame*   as.owin.SpatialPixelsDataFrame* as.owin.SpatialPolygons*        as.owin.tess                   
see '?methods' for accessing help and source code

So, assuming you have properly projected your data (as noted by @Ege Rubak), calling as.owin directly should work:

library(tigris)

county <- county_subdivisions(state = "Alabama", 
                              county = "Lee", 
                              class = "sf", 
                              progress_bar = FALSE)

county <- st_union(county)

county <- st_transform(county, crs = 6345)

window <- as.owin(county)

plot(window)