Saturday, 28 December 2019

clip - Crop simple features object in R


Is there a function to crop sf map object, similar to maptools::pruneMap(lines, xlim= c(4, 10), ylim= c(10, 15)) used for SpatialPolygon or SpatialLine?


I am considering st_intersection() but there can be proper way.



Answer



st_intersection is probably the best way. Find whatever way works best to get an sf object to intersect with your input. Here's a way using the convenience of raster::extent and a mix of old and new. nc is created by example(st_read):


st_intersection(nc, st_set_crs(st_as_sf(as(raster::extent(-82, -80, 35, 36), "SpatialPolygons")), st_crs(nc)))

I don't think you can coax st_intersection to not need an exact matching CRS, so either set both of them to NA or make sure they are the same. There's no easy tools for bbox/extent afaik, so using raster is good way to make things easy-ish.


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