How do I convert an sf object back to a SpatialPolygonsDataFrame?
I am running R 3.4.0 and sf version 0.4.1. The sf documentation mentions an as_Spatial function, but this isn't available in my install (for some reason).
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The coersion method is avalible at sf 0.4-1, what hapens when you try to call the function?– Jeffrey EvansCommented May 4, 2017 at 2:39
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4as(sf, "Spatial")– mdsumnerCommented May 4, 2017 at 6:23
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@Jeffrey Evans, Kazuhito's answer below replicates the problem (and provides a partial solition)– SimonCommented May 4, 2017 at 8:04
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2 Answers
I used
as(nc, 'Spatial')
as part 2 of the vignette by Edzer Pebesma indicated (Scroll to the bottom of the page).
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saw it. However I figured this out only recently and I felt the urge to put it into a proper answer when seeing this question ;)– andscharCommented May 5, 2017 at 7:46
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And it is important the accepted answer will not be overlooked by future readers.– KazuhitoCommented May 6, 2017 at 2:05
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1For this to truly work like a SPDF, I needed to do something like:
tmp <-as(nc, 'Spatial'), thentmpid <- sapply(slot(tmp, "polygons"), function(x) slot(x, "ID"))thenrow.names(tmp) <- tmpid– SimonCommented May 15, 2017 at 11:50 -
1what does 'truly work like a SPDF' mean? I see no disadvantage created by the conversion.– andscharCommented May 15, 2017 at 14:16
I had to use sf:::as_Spatial() as workaround.
library(sf)
nc <- st_read(system.file("shape/nc.shp", package="sf"))
# sf -> sp
nc_sp <- as_Spatial(nc$geom) # Error: could not find function "as_Spatial"
nc_sp <- sf:::as_Spatial(nc$geom) # This works
library(sp)
plot(nc_sp)
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Running
as(sf, "Spatial")by @mdsumner , I confirm it produces SpatialPolygonsDataFrame, which is better for your requirement. It seemsas_Spatial()takes sfc (ie geometry) only.– KazuhitoCommented May 4, 2017 at 8:08 -
1This function is a method and is ment to be call using as(). It is not exported as a function object which is why, to call it directly, you need ":::". Commented May 4, 2017 at 17:29
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it seems the as() function is no longer in the
sfpackage– mattadorCommented Aug 16, 2022 at 14:10 -