How to sp with sf

[edzer]

It would be nice to have a list of sp, rgeos and rgdal commands with the corresponding command in sf, e.g.

• sp::disaggregate -> sf::st_cast

I started this in the sf wiki

[tim-salabim]

This is great! Will be very helpful to update workflows. Thanks for these references!

[edzer]

See also here, calling for improvement.

[Robinlovelace]

Here's a challenge (as discussed with @Nowosad, example from vignette("over")) - how to do this with sf?

library(sp)
g = SpatialGrid(GridTopology(c(0, 0), c(1, 1), c(3, 3)))
p = as(g, "SpatialPolygons")
plot(p)

over(p[5], p, returnList = TRUE, minDimension = 0)
#> $g5
#> [1] 5 2 4 6 8 1 3 7 9
over(p[5], p, returnList = TRUE, minDimension = 1)
#> $g5
#> [1] 5 2 4 6 8
over(p[5], p, returnList = TRUE, minDimension = 2)
#> $g5
#> [1] 5

[Robinlovelace]

If I find out the answer I'll happily document it.

[edzer]

see #234 .

[Robinlovelace]

Thanks for the link - hadn't read that and really useful things in there that can solve that specific use case, as commented in that issue.

However, I don't think that thread addresses the question of how to "sp with sf" in that it does not provide a general replacement for the minDimension argument. People with perseverance and time could read-up on DE-9IM and find the right incantation but I think most people would find a minDimension argument, or alternative to it more user friendly, especially if they've already used minDimension in sp like me.

[edzer]

Here's a function that you could use in an lapply to get the same result as sp::over with returnList=TRUE:

s = st_as_sf(p)
> x = st_relate(s[5,], s)
> which_min_dim = function(x, n) {
	switch(as.character(n),
		"2" = which(substr(x, 1, 1) == "2"),
		"1" = which(substr(x, 5, 5) == "1"),
		"0" = which(substr(x, 5, 5) %in% c("0", "1")),
		stop("wrong value for n")
	)
}
> which_min_dim(x, 2)
[1] 5
> which_min_dim(x, 1)
[1] 2 4 5 6 8
> which_min_dim(x, 0)
[1] 1 2 3 4 5 6 7 8 9

[Robinlovelace]

Wow that's impressive! I've been thinking about this and was thinking of a helper function like st_over() that contain an interface for an equivalent of minDim. which_min_dim() should make that easy to do. I think that function will be useful if incorporated somewhere/somehow.

[rsbivand]

This comment has nothing to do with sf, and you attached it to a long-closed issue. If you want to ask about spdep, use issues there, not here.

…

On Mon, 4 May 2020 at 12:55, Arthur Katossky ***@***.***> wrote: Does it makes sense to document in the same way the equivalence with (relavant) functions from the spdep package? (I am especially thinking of all the series of neighbor functions: tri2nb, knearneigh etc.) — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#210 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACNZ3BCAKM6IAE2ZZEMJQ2LRP2NLVANCNFSM4C7FYJCQ> .

-- Roger Bivand Falsensvei 32 N-5063 Bergen, Norway Roger.Bivand@gmail.com

[katossky]

I kind-of realised that in the following minutes and suppressed the comment. (I am not sure I agree that it has nothing to do with sf though, but let's not discuss that here.) Thanks for taking the time to answer.